Journal articles on the topic 'Chiller systems'
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1
Leung, Michael Kwok Hi, Chi Yan Tso, Wei Wu, Zhanying Zheng, and Jingyu Cao. "Chillers of air-conditioning systems: An overview." HKIE Transactions 27, no. 3 (October 30, 2020): 113–27. http://dx.doi.org/10.33430/v27n3thie-2019-0055.
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In tropical and subtropical regions, air-conditioning commonly consumes the most energy in buildings. The chillers used in existing air-conditioning systems are largely based on thermodynamic vapour compression cycle because the cycle is highly effective, efficient and practical. Moreover, the system installation and operation are convenient when grid electricity is available. Popular vapour compression chiller types include air-cooled, water-cooled, seawater-cooled and oil-free chillers. In addition, thermal-driven absorption and adsorption chillers have become available in the market. Viable sources of thermal energy input include fuel combustion, renewable solar energy, waste heat, and so on. This paper provides an overview of different types of chillers and system configurations in terms of mechanisms, characteristics, energy efficiency, environmental performance and costs. The technical information and comparisons should help engineers select the chiller type in air-conditioning system design for achieving high sustainability.
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Dai, Ming He, Zhi Ping Zhou, and Xing Xue. "Test and Energy Consumption Analysis of Air-Conditioning Systems in Terminal Building of Guilin Liangjiang International Airport." Applied Mechanics and Materials 170-173 (May 2012): 2652–56. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.2652.
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In this paper, the operating conditions of air-conditioning systems in Terminal building of Guilin LiangJiang International Airport were tested and analysed. This paper mainly analyzes the influence of chilled water temperature on water chiller performance and derives the relationship of COP of water chiller and chilled water temperature difference between inlet and outlet , and provides reference for operation mode’s optimization of the air-conditioning system and energy consumption reduction of the whole building.
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Phu, Nguyen Minh. "Overall Optimization and Exergy Analysis of an Air Conditioning System Using a Series-Series Counterflow Arrangement of Water Chillers." International Journal of Air-Conditioning and Refrigeration 27, no. 04 (November 25, 2019): 1950034. http://dx.doi.org/10.1142/s2010132519500342.
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When water chillers are arranged in series-series counterflow (SSCF), the compressor lift of each chiller is decreased in comparison with that of water chillers in parallel. This means that the compressor power of SSCF chillers is lower than that of parallel chillers. In this paper, models of the main components in an air conditioning system were developed and verified to predict the behaviors of the whole system with respect to SSCF chillers. The results showed that performance was maximized with three SSCF chillers when the system was operated with normal set points. The performance was further improved to 26% and decreased with the number of SSCF chillers when the system was operated with optimal set points. The SSCF chiller system also demonstrated higher exergy efficiency regardless of the number of SSCF chillers. The irreversibility of components in SSCF chillers was rather low. However, the irreversibility of the cooling tower and cooling coil was slightly higher and lower, respectively, than those in the parallel chiller system.
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Zamanian, Erfan, Julian Shun, Carsten Binnig, and Tim Kraska. "Chiller." ACM SIGMOD Record 50, no. 1 (June 15, 2021): 15–22. http://dx.doi.org/10.1145/3471485.3471490.
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Distributed transactions on high-overhead TCP/IP-based networks were conventionally considered to be prohibitively expensive. In fact, the primary goal of existing partitioning schemes is to minimize the number of cross-partition transactions. However, with the new generation of fast RDMAenabled networks, this assumption is no longer valid. In this paper, we first make the case that the new bottleneck which hinders truly scalable transaction processing in modern RDMA-enabled databases is data contention, and that optimizing for data contention leads to different partitioning layouts than optimizing for the number of distributed transactions. We then present Chiller, a new approach to data partitioning and transaction execution, which aims to minimize data contention for both local and distributed transactions.
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Fekete, Alan D. "Chiller." ACM SIGMOD Record 50, no. 1 (June 15, 2021): 14. http://dx.doi.org/10.1145/3471485.3471489.
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Many computing researchers and practitioners may be surprised to find a "research highlight" which innovates on the way to process database transactions. Work in the early 1970s, by Turing winner Jim Gray and others, established a standard set of techniques for transaction management. These remain the basis of most commercial and open-source platforms [1], and they are still taught in university database classes. So why is important research still needed in this topic? The technology environment keeps evolving, and new performance characteristics mean that new algorithms and system designs become appropriate. This perspective will summarise the early work, and point to how the field has continued to progress.
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Kuczyńska, Agnieszka, and Władysław Szaflik. "Absorption and adsorption chillers applied to air conditioning systems." Archives of Thermodynamics 31, no. 2 (July 1, 2010): 77–94. http://dx.doi.org/10.2478/v10173-010-0010-0.
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Absorption and adsorption chillers applied to air conditioning systemsThis work presents an application possibility of sorption refrigerators driven by low temperature fluid for air conditioning of buildings. Thermodynamic models were formulated and absorption LiBr-water chiller with 10 kW cooling power as well as adsorption chiller with silica gel bed were investigated. Both of them are using water for desorption process with temperatureTdes= 80 °C. Coefficient of performance (COP) for both cooling cycles was analyzed in the same conditions of the driving heat source, cooling waterTc= 25 °C and temperature in evaporatorTevap= 5 °C. In this study, the computer software EES was used to investigate the performance of absorption heat pump system and its behaviour in configuration with geothermal heat source.
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SATHTHASIVAM, JAYAPRAKASH, GARY TANG, and KIM CHOON NG. "EVALUATION OF THE SIMPLE THERMODYNAMIC MODEL (GORDON AND NG UNIVERSAL CHILLER MODEL) AS A FAULT DETECTION AND DIAGNOSIS TOOL FOR ON-SITE CENTRIFUGAL CHILLERS." International Journal of Air-Conditioning and Refrigeration 18, no. 01 (March 2010): 55–60. http://dx.doi.org/10.1142/s2010132510000071.
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The application of Fault Detection and Diagnosis (FDD) could play a key role in operating chillers at optimum efficiency. As air-conditioning consumes a significant proportion (approximately 30% to 50%) of the total power consumption of a commercial building, an effective FDD tool is very much required for a reliable and economic chiller operation. In this paper, the renowned Simple Thermodynamic Model, STM (also known as Gordon and Ng Universal Chiller Model) was utilized to detect and diagnose some of the common faults in centrifugal chillers. Based on the readily available, nonintrusive, steady state measurements extracted from the on-site chillers, the STM model was regressed to obtain two physically meaningful coefficients, namely, Thermal Resistance and Internal Entropy Generation. These information-rich coefficients were then analyzed to evaluate the performances and the conditions of the chillers. Despite the large and yet complex on-site chiller operations, equipped with built-in heat recovery, such as economizer and intricate control mechanisms, the predictive and diagnostic capabilities of STM in detecting chiller faults has been successfully tested and evaluated based on the data collected from on-site centrifugal chillers. Faults like condenser fouling and reduction in condenser cooling water flow rate were succinctly captured by the STM model.
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Kaya, A., and A. Sommer. "Energy Management of Chillers by Multilevel Control and Optimization." Journal of Dynamic Systems, Measurement, and Control 107, no. 4 (December 1, 1985): 270–77. http://dx.doi.org/10.1115/1.3140735.
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This paper deals with multilevel control and optimization of a chiller system. The system consists of multiple chillers, feed pumps, and cooling towers. A multilevel control structure is presented. The first level contains control loops for chilled water temperature, vane position, and condenser water temperature. Second level controls provide supervisory adjustments of set points of first level controls. Third level is optimum load allocation of chillers and pumps. A fourth level supervisory deals with the coordination of conflicting goals of subsystems to provide a load strategy. Performance analysis (monitoring, trouble shooting) are also presented. A digital and distributed control system is utilized for implementation. The distributed system has a flexible architecture compatible for each level of control sophistication. It offers simple function blocks for digital control of first-level loops, as well as, the higher levels without any need of computer programming.
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Ayou, Dereje S., and Alberto Coronas. "New Developments and Progress in Absorption Chillers for Solar Cooling Applications." Applied Sciences 10, no. 12 (June 12, 2020): 4073. http://dx.doi.org/10.3390/app10124073.
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At present, novel, small-to-large capacity absorption chillers with unique technical features have emerged on the global market, and laboratory and pre-industrial prototypes have also been developed. These chillers have been designed for the efficient use of low-grade heat sources; some are air-cooled, small capacity systems; compact water/LiBr chillers; or solar-gas-fired single/double-effect chillers. Also, some advanced commercial absorption chillers have an extensive temperature glide in the driving heat stream (>30 K) which extracts approximately twice as much heat (~200%) as the single-effect chiller. This large temperature glide means that the chillers are well suited to solar thermal collector installations and district heating networks, and the extra driving heat increases cold production. Moreover, recent advances in R718 turbo compressor technologies have helped to solve the problems water/LiBr absorption chillers have in adapting to extreme operating conditions (e.g., high ambient temperature, >35 °C) by using a compressor-boosted absorption chiller configuration. This review paper presents and discusses the developments and progress in these absorption chiller technologies. In summary, the new absorption chillers may be useful for developing efficient, cost-effective, and robust solar cooling solutions that are needed to mitigate the unsustainable impact of the rising global demand for space cooling.
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Radchenko, Andrii M. "Gas turbine intake air cooling systems of combined type and their optimum designing." Joupnal of New Technologies in Environmental Science 5, no. 2 (June 30, 2020): 3–24. http://dx.doi.org/10.30540/jntes-2020-2.1.
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Turbine intake air cooling (TIAC) by absorption lithium-bromide chillers (ACh) utilizing the exhaust heat is considered as the most effective fuel saving technology for temperate climatic conditions. But the cooling potential of TIAC systems based on ACh of a simple cycle is limited by a comparatively increased chilled water temperature of about 7°C excluding cooling intake air lower than 15°C. The application of a refrigerant as a coolant enables deeper cooling intake air to 10°C and lower. The application of two-stage hybrid absorption-ejector chillers (AECh) with a refrigerant ejector chiller (ECh) as a low temperature stage makes it possible to increase the annual fuel saving approximately twice in temperate climate due to deeper cooling air as compared with ACh. Furthermore, this effect can be achieved with the sizes of TIAC system reduced by about 20 % due to determining the rational refrigeration capacity of AECh providing practically maximum annual fuel saving increment and the use of the current excessive refrigeration capacities to cover peaked loads.
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Adornado, Adonis P., Allan N. Soriano, and Vergel C. Bungay. "Assessment of Aqueous Lithium-based Salt Solutions as Working Fluid for Absorption Chillers using Aspen Plus." ASEAN Journal of Chemical Engineering 17, no. 2 (July 7, 2018): 51. http://dx.doi.org/10.22146/ajche.49555.
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Absorption chillers are a viable option for providing waste heat-powered coolingor refrigeration, thereby improving overall energy efficiency-less primary energy input,lower emissions, and cost savings. This study focuses on the assessment of aqueouslithium-based salt solutions as working fluid for absorption chiller in exploring thepossibility of developing new mixtures for absorption chillers to improve the performanceof the absorption refrigeration systems (ARSs). In this paper, the coefficient ofperformance (COP) of a single-effect absorption chiller using aqueous lithium-based saltsolutions (LiF-H2O, LiCl-H2O, LiBr-H2O, and LiI-H2O) as working fluid was assessed usingAspen Plus®. The simulation results obtained showed that the mass and energy were wellbalanced for all systems. Furthermore, a direct proportionality relationship between COPof absorption chillers and the van't Hoff factor, i of dissociated aqueous salt solutions wasobserved. The highest COP value is 0.8930 for LiI-H2O among others.
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Li, Jie, and Yong Qian Luo. "Study on Energy Materials with the Impact of Using Chilled Water Storage Systems on the Performance of Air Cooled Chillers." Applied Mechanics and Materials 327 (June 2013): 173–76. http://dx.doi.org/10.4028/www.scientific.net/amm.327.173.
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In the air conditioning (AC) industry chilled water storage (CWS) systems are one form of cool thermal storage technology that can be used to time shift the electrical load of the system from the peak day periods to off peak night time periods. In this paper the data for the actual exported and generated electrical energy obtained for the power stations has been used to estimate the electrical energy consumption and the peak electrical load of AC systems. It is estimated AC systems represent about 62% of the peak electrical load. The results demonstrate that CWS can reduce the peak electrical load of a chiller in an air cooled AC system by up to 100% and reduce the nominal chiller size by up to 33% depending up on the operating strategy adopted. This is achieved with only a 4% increase in power consumption of the chiller for all CWS strategies except for full storage where the energy consumption actually decreases by approximately 4%.
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Chen, Ching Liang, and Yung Chung Chang. "Power Consumption Saving of Chiller Water System for Semiconductor Factory in Taiwan." Advanced Materials Research 314-316 (August 2011): 1492–501. http://dx.doi.org/10.4028/www.scientific.net/amr.314-316.1492.
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Recently, the semiconductor manufacturing industry has exhibited not only fast growth, but intense power consumption. Consequently, reducing power consumption is critical for running reliability. A view of literature reveals that the power consumption of facility system is 56.6 % in the fabs. Among all facility systems, chiller plants are the largest energy users, consuming 27.2 % of the total power consumption. Therefore, saving power consumption for chiller plants involves a considerable economic benefit. In addition, cooling the water temperature further improves the efficiency of chillers. Hence, this report analyzes the optimal temperature between the chiller and cooling tower. Currently, controlling the chiller and cooling tower are separate processes, though, in fact, they should not be. This is because the water cooling temperature affects the efficiency of the chiller. Each reduced degree of the chiller condenser temperature reduces the electrical power by approximately 2 % in the cooling tower, in contrast to the chiller. Therefore, the optimal water cooling water temperature must be analyzed. The analysis method in this report is linear regression. First, determine the equations of power consumption for the chiller and cooling tower with variables representing the water cooling temperature, water supply temperature of the chiller, and outdoor loading and wet-bulb temperatures. Second, add the coefficient of the same variable to obtain the total power consumption equation for the chiller and cooling tower. The result shows the relationships of power consumption with water cooling temperature under identical conditions of the water cooling temperature, water supply temperature of chiller, and outdoor loading and wet-bulb temperatures. Finally, use the differential method to determine the optimal water cooling temperature.
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Jiao, Yan Hui. "The Impact of Using Mathematics Principles on the Performance of Chillers." Applied Mechanics and Materials 278-280 (January 2013): 165–68. http://dx.doi.org/10.4028/www.scientific.net/amm.278-280.165.
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In AC industry chilled water storage (CWS) systems are one form of cool thermal storage technology that can be used to time shift the electrical load of the system from the peak day periods to off peak night time periods. In this paper the data for the actual exported and generated electrical energy obtained for the power stations has been used to estimate the electrical energy consumption and the peak electrical load of AC systems. Since the chiller in an air cooled AC system represent more than 75% of the total electrical power consumed by an AC system during the peak demand period, the impact of using CWS systems with alternative operating strategies including partial(load leveling ),partial (demand limiting) and full load has been investigated. In our conclusions we estimate that approximately 45% of the total annual exported electrical energy is consumed solely by AC systems as a result of the very high ambient temperatures. Furthermore, it is estimated AC systems represent about 62% of the peak electrical load. The results demonstrate that CWS can reduce the peak electrical load of a chiller in an air cooled AC system by up to 100% and reduce the nominal chiller size by up to 33% depending up on the operating strategy adopted. This is achieved with only a 4% increase in power consumption of the chiller for all CWS strategies except for full storage where the energy consumption actually decreases by approximately 4%.
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Alonso, Serafín, Antonio Morán, Miguel Prada, Perfecto Reguera, Juan Fuertes, and Manuel Domínguez. "A Data-Driven Approach for Enhancing the Efficiency in Chiller Plants: A Hospital Case Study." Energies 12, no. 5 (March 2, 2019): 827. http://dx.doi.org/10.3390/en12050827.
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Large buildings cause more than 20% of the global energy consumption in advanced countries. In buildings such as hospitals, cooling loads represent an important percentage of the overall energy demand (up to 44%) due to the intensive use of heating, ventilation and air conditioning (HVAC) systems among other key factors, so their study should be considered. In this paper, we propose a data-driven analysis for improving the efficiency in multiple-chiller plants. Coefficient of performance (COP) is used as energy efficiency indicator. Data analysis, based on aggregation operations, filtering and data projection, allows us to obtain knowledge from chillers and the whole plant, in order to define and tune management rules. The plant manager software (PMS) that implements those rules establishes when a chiller should be staged up/down and which chiller should be started/stopped according different efficiency criteria. This approach has been applied on the chiller plant at the Hospital of León.
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Sztekler, Karol, Wojciech Kalawa, Wojciech Nowak, Sebastian Stefański, Jarosław Krzywański, and Karolina Grabowska. "Using the adsorption chillers for waste heat utilisation from the CCS installation." EPJ Web of Conferences 180 (2018): 02106. http://dx.doi.org/10.1051/epjconf/201818002106.
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Worldwide tendencies in the scope of environmental protection demonstrate the requirement for the limited carbon dioxide emission, that influences on the development of greenhouse effect. As a result of coal as a basic fuel used in the professional power industry, this industry sector is the greatest CO2 polluter and it means that works on the reduction of carbon dioxide in such industry are completely justified. In the IPSEpro programming environment, a reference block model for a conventional coal power station was elaborated, including the CO2 separation unit basing on the adsorption methods with the CO2 preparation installation to liquid state. Simulation researches were conducted with means of numeric techniques, that enabled the system analysis for the CO2 separation unit with the CO2 preparation system to the liquid state, as well as analysis was made for the use of chiller systems, basing on the adsorption technology for waste heat use originating from the compression of CO2 in a cascade system, as well as for potential opportunities for further exploitation of the produced chilled water in the CCS cycle. We analysed in these papers the opportunities for chiller systems application, based on the adsorption chillers in the CCS installation used for the reduction of CO2 emission in the coal power station and its influence on the operation of a power station cycle.
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Koppmann, Matthias, Raphael Lechner, Tom Goßner, and Markus Brautsch. "Assessment Methodology for Efficiency, CO2-Emissions and Primary Energy Consumption for Refrigeration Technologies in the Industry." Applied Mechanics and Materials 882 (July 2018): 215–20. http://dx.doi.org/10.4028/www.scientific.net/amm.882.215.
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Process cooling and air conditioning are becoming increasingly important in the industry. Refrigeration is still mostly accomplished with compression chillers, although alternative technologies are available on the market that can be more efficient for specific applications. Within the scope of the project “EffiCool” a technology toolbox is currently being developed, which is intended to assist industrials users in selecting energy efficient and eco-friendly cooling solutions. In order to assess different refrigeration options a consistent methodology was developed. The refrigeration technologies are assessed regarding their efficiency, CO2-emissions and primary energy consumption. For CCHP systems an exergetic allocation method was implemented. Two scenarios with A) a compression chiller and B) an absorption chiller coupled to a natural gas CHP system were calculated exemplarily, showing a greater overall efficiency for the CCHP system, although the individual COP of the chiller is considerably lower.
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Zamhuri, Muhammad Ikhwan, Haslenda Hashim, and Ho Wai Shin. "Optimal Design of Integrated Chiller Capacity with Ice Thermal Storage for Commercial Buildings through Cooling System Cascade Analysis." International Journal of Innovative Technology and Exploring Engineering 10, no. 2 (December 10, 2020): 165–75. http://dx.doi.org/10.35940/ijitee.b8301.1210220.
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Chilled water air conditioning system is used to supply cooling systems in large capacity for industrial processes and commercial buildings. Air conditioners contribute more than 60 percent of electricity consumption in buildings. District Cooling System (DCS) technology comprises a central chiller plant which provides advantage compared to local air conditioning system. It has higher efficiency, uses less power in system operation, allows more usable space in buildings, and can be operated with minimum manpower while handling same amount of cooling load. The integration of a chiller with ice thermal storage (ITS) offers more operational flexibility while reducing space cooling expenses. This paper presents a systematic framework for design and operation of District Cooling Plant (DCP) comprising an integrated chiller and ice thermal storage system. The Cooling System Cascade Analysis (COSCA) based on pinch analysis is constructed to determine the chiller optimal size and ice thermal storage capacity. The District Cooling System configuration for this study comprises a cooling tower, chiller (centrifugal, variable centrifugal, glycol) and ice thermal storage system. The application of this technique to fulfil 66,284 refrigerant tonne hour (RTH) cooling load demand from commercial buildings reveals the optimal capacity of the chiller is 3068.91 refrigerant tonne (RT), ice tank rating at 989 refrigerant tonne (RT) and ice tank capacity is 9892.75 refrigerant tonne hour (RTH).
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Nugraha, Anggara Trisna, and Lailia Nur Safitri. "Optimization of Central Air Conditioning Plant by Scheduling the Chiller Ignition for Chiller Electrical Energy Management." Indonesian Journal of electronics, electromedical engineering, and medical informatics 3, no. 2 (May 29, 2021): 76–83. http://dx.doi.org/10.35882/ijeeemi.v3i2.7.
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Currently, the demand for electrical energy in homes, buildings, and industry is increasing, in line with population and economic growth. Of course, because of the massive use of electrical energy, it is necessary to increase efficiency. Large shopping malls in some countries are the biggest consume electricity, especially when it comes to cooling systems. Therefore, it is necessary to save energy in shopping centers. Because there are still few tenants and shopping centers that are relatively quiet, the mall's energy consumption is low, so it requires increasing energy-efficient consumption efficiency by optimizing power management and calculating the chiller performance coefficient (COP). This research aims to increase the chiller performance coefficient (COP) to save energy in shopping centers. The optimization method used is to make changes to the chiller ignition schedule when it's used in malls. Through the analysis from this research, it was found that the COP increased to 0.584, and the value before optimization was 6.181. With increasing COP, the chiller performance will increase. The effect of increasing the chiller's performance could optimize the electrical energy efficiency of the chiller in 138.82 kWh/day
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Jia, Yongzhong, and T. Agami Reddy. "Characteristic Physical Parameter Approach to Modeling Chillers Suitable for Fault Detection, Diagnosis, and Evaluation." Journal of Solar Energy Engineering 125, no. 3 (August 1, 2003): 258–65. http://dx.doi.org/10.1115/1.1567317.
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Model-based fault detection and diagnosis approaches based on statistical models for fault-free performance concurrently require a fault classifier database for diagnosis. On the other hand, a model with physical parameters would directly provide such diagnostic ability. In this paper, we propose a generic model development approach, called the characteristic parameter approach, which is suitable for large engineering systems that usually come equipped with numerous sensors. Such an approach is applied to large centrifugal chillers, which are generally the single most expensive piece of equipment in heating, ventilating, air-conditioning, and refrigeration systems. The basis of the characteristic parameter approach is to quantify the performance of each and every primary component of the chiller (the electrical motor, the compressor, the condenser heat exchanger, the evaporator heat exchanger, and the expansion device) by one or two performance parameters, the variation in magnitude of which is indicative of the health of that component. A hybrid inverse model is set up based on the theoretical standard refrigeration cycle in conjunction with statistically identified component models that correct for non-standard behavior of the characteristic parameters of the particular chiller. Such an approach has the advantage of using few physically meaningful parameters (as against using the numerous sensor data directly), which simplifies the detection phase while directly providing the needed diagnostic ability. Another advantage to this generic approach is that the identification of the correction models is simple and robust, since it requires regression rather than calibration. The entire methodology has been illustrated with actual monitored data from two centrifugal chillers (one a laboratory chiller and the other a field operated chiller). The sensitivity of this approach to sensor noise has also been investigated.
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Moreno Garcia, Francisco Ernesto, Enio Pedone Bandarra Filho, and Jose Alexander Becerra Vargas. "Controladores fuzzy adaptativos para la optimización de un sistema chiller." Respuestas 16, no. 1 (January 15, 2011): 5–12. http://dx.doi.org/10.22463/0122820x.406.
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Los sistemas chiller, son ciclos de compresión por vapor utilizados en aplicaciones industriales y residenciales, operados de forma clásica e inadecuada desde el punto de vista del consumo de energía. Este trabajo experimental desarrollado en el laboratorio de Energía y sistemas térmicos de la Universidad Federal de Uberlândia (UFU), investiga algunas ventajas en el uso del compresor a velocidad variable y válvula de expansión electrónica con el objetivo de reducir el consumo de energía y elevar el coeficiente de eficacia (COP) de estos sistemas chillers. En estas condiciones es propuesto un modelo experimental basado en técnicas de planeamiento experimental, aplicando herramientas de superficie de respuesta. Este modelo permite estimar el comportamiento dinámico de la frecuencia del compresor, para contribuir a lazos de control aplicando estrategias fuzzy adaptativas, presentando un excelente rendimiento en el sistema, buscando mínimos grados de supercalentamiento en el orden de los 7 °C y alcanzando mejores regiones de COP.Palabras clave: Chiller, Control, Fuzzy, Refrigeración, Supercalentamiento, Superficie. Abstract The chiller systems are vapor compression cycles used in industrial and residential applications, operated a classical control and inadequate under energy consumption point of view. The experimental work, development in the Energy and Thermal System Laboratory of Federal University of Uberlandia (UFU), investigates some advantages of the use of variable speed compressor and electronic expansion valves focusing on energy consumption reduction and increase of the coefficient of performance, (COP) of these chillers systems. In these conditions, a proposed model experimentally based on experimental planning techniques, applying tools of answer surfaces. This model allows the estimative of the dynamic behavior of the compressor frequency to contribute in the control mesh applying adaptative fuzzy strategies, showing a good performance on the system, searching a minimum degree of superheating in the order of the 7°C and reaching on the bests COP zones.Keywords: Chiller, Control, Fuzzy, Refrigeration, Superheating, Surface.
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Yan, Chengchu, Qi Cheng, and Hao Cai. "Life-Cycle Optimization of a Chiller Plant with Quantified Analysis of Uncertainty and Reliability in Commercial Buildings." Applied Sciences 9, no. 8 (April 14, 2019): 1548. http://dx.doi.org/10.3390/app9081548.
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Conventional and most optimal design methods for chiller plants often address the annual cooling load distribution of buildings and their peak cooling loads based on typical meteorological year (TMY) data, while the peak cooling load only appears a few times during the life-cycle and the sized chiller plant usually operates within its low efficient region. In this paper, a robust optimal design method based on life-cycle total cost was employed to optimize the design of a chiller plant with quantified analysis of uncertainty and reliability. By using the proposed design method, the optimized chiller plant can operate at its highly efficient region under various cooling load conditions, and provide sufficient cooling capacity even alongside some equipment/systems with failures. The minimum life-cycle total cost, which consists of the capital cost, operation, and availability-risk cost, can be achieved through optimizing the total cooling capacity and the numbers/sizes of chillers. A case study was conducted to illustrate the detailed implementation process of the proposed method. The performance of this design method was evaluated by comparing with that of other design methods.
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Henze, Gregor P. "Parametric Study of a Simplified Ice Storage Model Operating Under Conventional and Optimal Control Strategies*." Journal of Solar Energy Engineering 125, no. 1 (January 27, 2003): 2–12. http://dx.doi.org/10.1115/1.1530629.
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A simplified ice storage system model was developed in which the icemaking mode is reflected by a higher power consumption per unit cooling than in chilled-water mode. The performance of four control strategies for ice storage systems is evaluated. The four control strategies investigated are chiller-priority and constant-proportion as conventional, instantaneous controls, while storage-priority and optimal control represent sophisticated controls employing load forecasting. Six parameters were investigated with respect to their influence on the ice storage system performance: Storage losses, utility rate structures, rate periods, penalty for icemaking, storage capacity, and the impact of load forecasting. Optimal control was determined to provide maximal operating cost savings. The storage-priority control yields operating costs only slightly higher than those of optimal control. Chiller-priority control realized savings that were typically on the order of 50% of what is theoretically possible (optimal control). Constant-proportion control proved to be a simple control strategy yielding higher savings than chiller-priority, yet lower than storage-priority control.
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Viscito, Luca, Gianluca Lillo, Giovanni Napoli, and Alfonso William Mauro. "Waste Heat Driven Multi-Ejector Cooling Systems: Optimization of Design at Partial Load; Seasonal Performance and Cost Evaluation." Energies 14, no. 18 (September 9, 2021): 5663. http://dx.doi.org/10.3390/en14185663.
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In this paper, a seasonal performance analysis of a hybrid ejector cooling system is carried-out, by considering a multi-ejector pack as expansion device. A 20 kW ejector-based chiller was sized to obtain the optimal tradeoff between performance and investment costs. The seasonal performance of the proposed solution was then evaluated through a dynamic simulation able to obtain the performance of the designed chiller with variable ambient temperatures for three different reference climates. The optimized multi-ejector system required three or four ejectors for any reference climate and was able to enhance the system performance at partial load, with a significant increase (up to 107%) of the seasonal energy efficiency ratio. The proposed system was then compared to conventional cooling technologies supplied by electric energy (electrical chillers EHP) or low-grade heat sources (absorption chillers AHP) by considering the total costs for a lifetime of 20 years and electric energy-specific costs for domestic applications from 0.10 to 0.50 €/kWhel. The optimized multi-ejector cooling system presented a significant convenience with respect to both conventional technologies. For warmer climates and with high electricity costs, the minimum lifetime for the multi-ejector system to achieve the economic break-even point could be as low as 1.9 years.
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Ho, Wai Tung, and Fu Wing Yu. "Chiller system performance management with market basket analysis." Facilities 39, no. 9/10 (March 19, 2021): 667–87. http://dx.doi.org/10.1108/f-09-2020-0107.
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Purpose This study aims to apply association rule mining (ARM) to uncover specific associations between operating components of a chiller system and improve its coefficient of performance (COP), hence reducing the electricity use of buildings with central air conditioning. Design/methodology/approach First, 13 operating variables were identified, comprising measures of temperatures and flow rates of system components and their switching statuses. The variables were grouped into four bins before carrying out ARM. Strong rules were produced to associate the variables and switching statuses with different COP classes. Findings The strong rules explain existing constraints on practising chiller sequencing and prioritise variables for optimisation. Based on strong rules for the highest COP class, the optimal operating strategy involves rescheduling chillers and their associated components in pairs during a high load operation. Resetting the chilled water supply temperature is the next best strategy, followed by resetting the condenser water entering temperature, subject to operating constraints. Research limitations/implications This study considers the even frequency method with four bins only. Replication work can be done with other discretisation methods and different numbers of classes to compare potential differences in the bin ranges of the optimised variables. Practical implications The strong rules identified by ARM highlight associations between variables and high or low COPs. This supports the selection of critical variables and the operating status of system components to maximise the COP. Tailor-made optimisation strategies and the associated electricity savings can be further evaluated. Originality/value Previous studies applied ARM for chiller fault detection but without considering system performance under the interaction of different components. The novelty of this study is its demonstration of ARM’s intelligence at discovering associations in past operating data. This enables the identification of tailor-made energy management opportunities, which are essential for all engineering systems. ARM is free from the prediction errors of typical regression and black-box models.
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Villa, Alvaro Antonio Ochoa, José Ângelo Peixoto da Costa, and Carlos Antonio Cabral dos Santos. "Energetic Analysis using theoretical modeling and the characteristic equation method in a small absorption chiller with LiBr/H2O." Acta Scientiarum. Technology 40, no. 1 (April 26, 2018): 34969. http://dx.doi.org/10.4025/actascitechnol.v40i1.34969.
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This paper sets out to examine a small absorption chiller that uses the pair LiBr/ H2O with a 4.5 kW nominal capacity, using theoretical modeling and the characteristic equation method. The idea is to compare two ways of simulating and evaluating absorption systems by analyzing the temperatures and flow rates of external hot, chilled and cold water circuits, as well as the values of the overall heat transfer coefficients of each component. Energetic analysis is based on conserving mass and energy by taking into consideration the overall heat transfer coefficients and their respective areas via the UA products of the 5 components of the absorption chiller. The characteristic equation method is based on Duhring’s rule of the internal temperature which is founded on saturation mean temperatures and the Duhring coefficient (B). The results of comparing the activation of thermal power and the cooling capacity of the Rotartica absorption chiller, obtained by theoretical modeling and from the characteristic equation values, were good since the mean relative errors found were 4% lower for most of the operating conditions examined.
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Lima, Alvaro A. S., Gustavo de N. P. Leite, Alvaro A. V. Ochoa, Carlos A. C. dos Santos, José A. P. da Costa, Paula S. A. Michima, and Allysson M. A. Caldas. "Absorption Refrigeration Systems Based on Ammonia as Refrigerant Using Different Absorbents: Review and Applications." Energies 14, no. 1 (December 24, 2020): 48. http://dx.doi.org/10.3390/en14010048.
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The interest in employing absorption refrigeration systems is usually related to electricity’s precariousness since these systems generally use thermal rejects for their activation. The application of these systems is closely linked to the concept of energy polygeneration, in which the energy demand to operate them is reduced, which represents their main advantage over the conventional vapor compression system. Currently, the solution pairs used in commercial absorption chillers are lithium bromide/water and ammonia/water. The latter pair has been used in air conditioning and industrial processes due to the ammonia operation’s low temperature. Few review papers on absorption chillers have been published, discussing the use of solar energy as the input source of the systems, the evolution of the absorption refrigeration cycles over the last decades, and promising alternatives to increase the performance of absorption refrigeration systems. There is a lack of consistent studies about designing requirements for absorption chillers, so an updated review covering recent advances and suggested solutions to improve the use and operation of those absorption refrigeration systems using different working fluids is relevant. Hence, this presents a review of the state-of-the-art of ammonia/absorbent based absorption refrigeration systems, considering the most relevant studies, describing the development of this equipment over the years. The most relevant studies in the open literature were collected to describe this equipment’s development over the years, including thermodynamic properties, commercial manufacturers, experimental and numerical studies, and the prototypes designed and tested in this area. The manuscript focuses on reviewing studies in absorption refrigeration systems that use ammonia and absorbents, such as water, lithium nitrate, and lithium nitrate plus water. As a horizon to the future, the uses of absorption systems should be rising due to the increasing values of the electricity, and the environmental impact of the synthetic refrigerant fluids used in mechanical refrigeration equipment. In this context, the idea for a new configuration absorption chiller is to be more efficient, pollutant free to the environment, activated by a heat substantiable source, such as solar, with low cost and compactness structure to attend the thermal needs (comfort thermal) for residences, private and public buildings, and even the industrial and health building sector (thermal processes). To conclude, future recommendations are presented to deal with the improvement of the refrigeration absorption chiller by using solar energy, alternative fluids, multiple-effects, and advanced and hybrid configurations to reach the best absorption chiller to attend to the thermal needs of the residential and industrial sector around the world.
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Acerbi, Federica, Mirco Rampazzo, and Giuseppe De Nicolao. "An Exact Algorithm for the Optimal Chiller Loading Problem and Its Application to the Optimal Chiller Sequencing Problem." Energies 13, no. 23 (December 2, 2020): 6372. http://dx.doi.org/10.3390/en13236372.
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The optimal management of multiple chiller systems calls for the solution of the so-called optimal chiller loading (OCL) problem. Due to the interplay of continuous and logical constraints, OCL is an NP-hard problem, so that a variety of heuristic algorithms have been proposed in the literature. Herein, an algorithm for its exact solution, named X-OCL, is developed under the assumption that the chillers’ power consumption curves are quadratic. The proposed method hinges on a decomposition of the solution space so that the overall OCL problem is decomposed to a set of equality constrained quadratic programming problems that can be solved in closed form. By applying the new X-OCL solver to well known case studies, we assess and compare the performances of several literature algorithms, highlighting also some errors in the published results. Moreover, X-OCL is used to design a greedy optimal chiller sequencing (OCS) solver, called X-OCS. The X-OCS is tested on two literature benchmarks and on the model of the heating, ventilation and air-conditioning (HVAC) system of a semiconductor plant, over a two-year period. The performances of X-OCS are remarkably close to the theoretical optimal performance.
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Figaj, Rafał, and Maciej Żołądek. "Operation and Performance Assessment of a Hybrid Solar Heating and Cooling System for Different Configurations and Climatic Conditions." Energies 14, no. 4 (February 21, 2021): 1142. http://dx.doi.org/10.3390/en14041142.
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Energy needs of air conditioning systems are constantly growing worldwide, due to climate change and growing standards of buildings. Among the possible systems, solar heating and cooling based on reversible heat pumps and thermally driven chillers are a viable option for ensuring space heating and cooling for different users. The high installation costs are a limit to their diffusion, however, under specific circumstances (climate, type of the building, type of the user, etc.), the investment in this technology can be profitable in a long term. The presented paper describes an energy-economic assessment of a solar heating and cooling system integrating a solar dish concentrator with thermal collectors coupled with a reversible heat pump and an absorption or adsorption chiller. The system integrated with a household building is developed and dynamically simulated in the Transient System Simulation (TRNSYS) environment under different circumstances –adoption of absorption or adsorption chiller, use of auxiliary thermal energy to drive the sorption chillers, and locality. The results show that space cooling demand in Cracow is matched by solar energy, in a range between 49.0 and 97.6%, while for Naples the space cooling demand is provided by solar heat from 46.1 to 99.1% depending on the adopted sorption chiller and or the use of auxiliary heat for a natural gas boiler. The proposed system is not profitable in case Cracow, since a Simple Pay Back period of about 20 years is achieved. Conversely, case of Naples, the same index achieves a value between 8 and 12 years showing that the proposed system may be a viable solution for heating and cooling installation.
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Assadi, Morteza Khalaji, Hamidreza Akhavan Armaki, and Mahmoud Zendeh Del. "Technical-Economic Analysis of Steam Double Effect Absorption Chiller-Heaters Equipped with Solar Heat Pipe System." Applied Mechanics and Materials 465-466 (December 2013): 327–34. http://dx.doi.org/10.4028/www.scientific.net/amm.465-466.327.
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The aim of this research is to indicate a steam double effect chiller-heater equipped with solar heat pipe in a certain space with the area of 975 m2 located in Tehran, which is currently equipped with a direct-fired single effect absorption chiller-heater. Thereafter , the most obvious differences of the two chiller-heater systems are compared: the solar cooling system increases coefficient of performance as high as 0.54, decreases CO2 dissemination by 829 tons in each year, and reduces energy consumption by 1552.42 MWh/Yr. Economic analysis of the two systems using break-even-point showed that the use of solar system is attractive in applications that have excess thermal energy, and the conversion of this energy to higher value energy markets is to be more profitable than absorption gas-fired system from 13th year on. Keywords: Technical-economic analysis, energy optimization, solar chiller, absorption chiller-heater, solar heat pipe.
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Ha, Ju-wan, Soolyeon Cho, Hwan-yong Kim, and Young-hak Song. "Annual Energy Consumption Cut-Off with Cooling System Design Parameter Changes in Large Office Buildings." Energies 13, no. 8 (April 19, 2020): 2034. http://dx.doi.org/10.3390/en13082034.
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A variety of greenhouse gas reduction scenarios have been proposed around the world to ensure sustainable developments and strengthen the global response to the climate change. To cope with this, it is urgently needed to reduce the amount of energy used for the heating, ventilating, air conditioning, and refrigerating (HVAC&R) systems in large buildings. This study discusses the reduction of cooling energy in large office buildings through the minimization of changes in components and equipment, such as heat source equipment and pumps, changes in the layout and operating methods of chilled water circulation pumps, and changes in the temperatures of chilled and condenser water. To do this, this study targeted an entire cooling system consisting of a hydronic system, a chiller, and a cooling tower, and conducted a quantitative analysis of the energy consumption and of the reduction achieved through a change in the pumping system type in the cooling system and a change in the Korean standard design and temperature of chiller and cooling tower via EnergyPlus simulations. The simulation results showed a cooling energy reduction of 103.2 MWh/yr, around 15.7%, where the primary constant-speed system (Case A) was changed to a primary variable-speed pump (Case B) in the configuration with a chilled water circulation pump. To reduce the cooling energy further, annually 142.3 MWh, around 21.7%, Case C in this study changed the outlet temperature of the chiller and temperature difference from 7 °C, 5 K to 9 °C, 9 K. Finally, when applying a change in the condenser water production temperature from 32 to 23.9 °C in accordance with ASHRAE Standard 90.1 for Case D, a cooling energy saving of 182.4 MWh/yr was observed, which is about 27.8%.
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Marjianto, Agus, Hafthirman Hafthirman, and Prihadi Setyo Darmanto. "ENERGY AND COST SAVING POTENTIAL OF HOTEL AIR CONDITIONING USING MAGNETIC BEARING CHILLER IN JAKARTA." International Journal of Innovation in Mechanical Engineering and Advanced Materials 3, no. 1 (June 4, 2021): 1. http://dx.doi.org/10.22441/ijimeam.v3i1.11356.
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The use of magnetic bearing chillers in hotel air conditioning systems is an opportunity for energy or cost savings. This study will compare the electrical energy consumption and cost analysis of the centralized air conditioning system using magnetic bearing chiller that uses variable flow to another air conditioning system such as the centralized air conditioning using constant flow chiller and the VRF split air conditioning system at Hotel A in Jakarta. The calculation of energy consumption for each air conditioning system is carried out for a year. Meanwhile, the cost analysis will be carried out using the life cycle cost method for 20 years. The air conditioning system which has the least energy consumption and has the lowest life cycle cost is the best air conditioning system for this hotel building. The maximum cooling load that occurs in Hotel A is 3,281 kW. From the results of energy calculations and cost analysis, a centralized air conditioning system with magnetic bearing chiller with variable flow is the best choice to Hotel A or similar building to Hotel A, with IKE (Intensitas Konsumsi Energi) value of 84 kWh/(m2.year), and a total cost of 78,873,678,478.00 IDR for a period of 20 years.
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Shin, Mi-Su, Ji-Su Choi, and Kyu-Nam Rhee. "Cooling Capacity and Energy Performance of Open-Type Ceiling Radiant Cooling Panel System with Air Circulators." Energies 14, no. 1 (December 22, 2020): 5. http://dx.doi.org/10.3390/en14010005.
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Ceiling radiant cooling panel (CRCP) systems are being increasingly applied to commercial buildings due to their high thermal comfort level and energy efficiency. It is recommended that CRCP systems should be operated at a relatively high chilled water temperature to prevent condensation and save energy. However, even though a high chilled water temperature is effective for achieving condensation-free operation and high chiller efficiency, it can lead to insufficient cooling capacity. In this study, a method of enhancing the cooling capacity of CRCP systems was investigated through mock-up chamber tests. The open-type installation of CRCPs and the combination of air circulators were used to enhance the cooling capacity and energy performance of CRCP systems. Experimental results showed that compared to a conventional CRCP system, the cooling capacity of an open-type CRCP system with air circulators increased by up to 26.2%, and its cooling energy consumption decreased by up to 26.4%. Additionally, the open-type CRCP system with air circulators reduced the difference between the room air temperature and mean chilled water temperature. Thus, the proposed system can operate at a relatively high chilled water temperature, which is effective for reducing condensation risk and cooling energy consumption.
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Retezan, Adrian, and Szilveszter Geyer Ehrenberg. "Optimising the Number of Pumps and Balancing Valves in Chilled Water Distribution Systems." E3S Web of Conferences 111 (2019): 01071. http://dx.doi.org/10.1051/e3sconf/201911101071.
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Everyday life does involve use of cooling systems for different areas and scenarios. We use them to keep our thermal comfort level at optimum, either to get rid of some extra heat from technological systems. From various cooling solutions, one and very common system is the chilled water system, where centralised chiller plants produce the cooling energy and all terminal units do receive cooling energy using a distribution loop. According to statistical data, electrical energy consumption of pumps might be up to 17% of entire electrical use of the cooling plant. When designing our cooling system loads during operation will not be same all the time. Variation must be treated accordingly, therefore to get best efficiency of the system, we must get a good control. Beside shut-off motorised valves our balancing must be considered in different scenarios. The paper looks to summarize the challenges in getting a good balancing and energy efficiency in chilled water distribution system.
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Buck, R., and S. Friedmann. "Solar-Assisted Small Solar Tower Trigeneration Systems." Journal of Solar Energy Engineering 129, no. 4 (March 27, 2007): 349–54. http://dx.doi.org/10.1115/1.2769688.
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Solar-hybrid gas turbine power systems offer a high potential for cost reduction of solar power. Such systems were already demonstrated as test systems. For the market introduction of this technology, microturbines in combination with small solar tower plants are a promising option. The combination of a solarized microturbine with an absorption chiller was studied; the results are presented in this paper. The solar-hybrid trigeneration system consists of a small heliostat field, a receiver unit installed on a tower, a modified microturbine, and an absorption chiller. The components are described, as well as the required modifications for integration to the complete system. Several absorption chiller models were reviewed. System configurations were assessed for technical performance and cost. For a representative site, a system layout was made, using selected industrial components. The annual energy yield in power, cooling, and heat was determined. A cost assessment was made to obtain the cost of electricity and cooling power, and eventually additional heat. Various load situations for electric and cooling power were analyzed. The results indicate promising niche applications for the solar-assisted trigeneration of power, heat, and cooling. The potential for improvements in the system configuration and the components is discussed, also the next steps toward market introduction of such systems.
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Liu, C. W., and Y. K. Chuah. "The Effects of Capacity Coupling and Wet Air Return on the Energy Performance of Chiller-Cooling Tower Systems." Journal of Mechanics 27, no. 4 (December 2011): N25—N31. http://dx.doi.org/10.1017/jmech.2011.64.
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ABSTRACTThis study uses a novel concept of capacity coupling of chiller-cooling tower system to investigate the system energy performance. System performance factor (SPF) of the chiller-cooling tower system is used in the analysis. A regression function is obtained for hourly reset of condensing water temperature so to achieve maximum SPF. The regression function includes parameters such as ambient wet bulb temperature, chiller load ratio, tower capacity ratio, and a dimensionless relative efficiency of chiller and cooling tower. The regression function has an R2 close to 1 compared to the computed results. It is found that for capacity coupling ratio of 1.1 ∼ 1.6, SPF would increase by about 3 ∼ 6% compared with a typical base control. The effect of wet air return is presented as an equivalent wet bulb temperature. It has been found that SPF would decrease significantly when higher equivalent wet bulb temperature occurs at the tower inlet.
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Albieri, Michele, Alessandro Beghi, Cristian Bodo, and Luca Cecchinato. "Advanced control systems for single compressor chiller units." International Journal of Refrigeration 32, no. 5 (August 2009): 1068–76. http://dx.doi.org/10.1016/j.ijrefrig.2008.10.005.
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Krzywanski, Jaroslaw, Karolina Grabowska, Marcin Sosnowski, Anna Żyłka, Karol Sztekler, Wojciech Kalawa, Tadeusz Wójcik, and Wojciech Nowak. "Modeling of a re-heat two-stage adsorption chiller by AI approach." MATEC Web of Conferences 240 (2018): 05014. http://dx.doi.org/10.1051/matecconf/201824005014.
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A distinct advantage of adsorption chillers is their ability to be driven by heat of near ambient temperature. However the performance of the thermally driven adsorption systems is lower than that of other heat driven heating/cooling systems. It is the result of a poor heat transfer coefficient between the bed and the immersed heating surfaces of a built-in heat exchanger system. The aim of this work is to study the effect of thermal conductance values as well as other design parameters on the performance of a re-heat two-stage adsorption chiller. One of the main energy efficiency factors in cooling production, i.e. cooling capacity (CC) for wide-range of both design and operating parameters is analyzed in the paper. Moreover, the work introduces artificial intelligence (AI) approach for the optimization study of the adsorption cooler. The Adaptive Neuro – Fuzzy Inference System (ANFIS) was employed in the work. The developed ANFIS model can be applied for optimizations purposes and may constitute a submodel or a separate module in engineering calculations, capable to predict the CC of the re-heat two-stage adsorption chiller.
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Krzywanski, Jaroslaw, Karolina Grabowska, Marcin Sosnowski, Anna Zylka, Karol Sztekler, Wojciech Kalawa, Tadeusz Wojcik, and Wojciech Nowak. "An adaptive neuro-fuzzy model of a re-heat two-stage adsorption chiller." Thermal Science 23, Suppl. 4 (2019): 1053–63. http://dx.doi.org/10.2298/tsci19s4053k.
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Since the adsorption chillers do not use primary energy as driving source the possibility to employ low temperature waste heat sources in cooling energy production receives nowadays much attention of the industry and science community. However, the performance of the thermally driven adsorption systems is lower than that of other heat driven heating/cooling systems. Low coefficients of performance are one of the main disadvantages of adsorption coolers. It is the result of a poor heat transfer coefficient between the bed and the immersed heating surfaces of a built-in heat exchanger system. The purpose of this work is to study the effect of thermal conductance values of sorption elements and evaporator as well as other design parameters on the performance of a re-heat two-stage adsorption chiller. One of the main energy efficiency factors in cooling production, i. e. cooling capacity for wide-range of both design and operating parameters is analyzed in the paper. Moreover, the work introduces artificial intelligence approach for the optimization study of the adsorption cooler. The ANFIS was employed in the work. The increase in both the bed and evaporator conductance provides better performance of the considered innovative adsorption chiller. The highest obtained value of cooling capacity is 21.7 kW and it can be achieved for the following design and operational parameters of the considered re-heat two-stage adsorption chiller: Msorb = 40 kg, t = 1300 s, T = 80?C, Csorb/Cmet = 50, hAsorb = 4000 W/K, hAevap = 4000 W/K.
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Kadam, Sambhaji T., Ibrahim Hassan, Mohammad Azizur Rahman, Athanasios I. Papadopoulos, and Panos Seferlis. "Review on Modeling of Vapor Compression Chillers: District Cooling Perspective." International Journal of Air-Conditioning and Refrigeration 28, no. 02 (June 2020): 2030003. http://dx.doi.org/10.1142/s2010132520300037.
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Energy consumption and its associated consequences can be reduced by implementing district cooling strategies that supply low temperature water to a wide range of end users through chillers and distribution networks. Adequate understanding, performance prediction and further optimization of vapor compression chillers used widely in district cooling plants have been a subject of intense research through model-based approaches. In this context, we perform an extensive review of different modeling techniques used for predicting steady-state or dynamic performance of vapor compression liquid chillers. The explored modeling techniques include physical and empirical models. Different physical models used for vapor compression chillers, based on physics laws, are discussed in detail. Furthermore, empirical models (based on artificial neural networks, regression analysis) are elaborated along with their advantages and drawbacks. The physical models can depict both steady- and unsteady-state performance of the vapor compression chiller; however, their accuracy and physical realism can be enhanced by considering the geometrical arrangement of the condenser and evaporator and validating them for various ecofriendly refrigerants and large system size (i.e., cooling capacity). Apparently, empirical models are easy to develop but do not provide the necessary physical realism of the process of vapor compression chiller. It is further observed that DC plants/networks have been modeled from the point of view of optimization or integration but no efforts have been made to model the chillers with multiple VCR cycles. The development of such models will facilitate to optimize the DC plant and provide improved control strategies for effective and efficient operation.
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Peesel, Ron-Hendrik, Florian Schlosser, Henning Meschede, Heiko Dunkelberg, and Timothy Walmsley. "Optimization of Cooling Utility System with Continuous Self-Learning Performance Models." Energies 12, no. 10 (May 20, 2019): 1926. http://dx.doi.org/10.3390/en12101926.
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Prerequisite for an efficient cooling energy system is the knowledge and optimal combination of different operating conditions of individual compression and free cooling chillers. The performance of cooling systems depends on their part-load performance and their condensing temperature, which are often not continuously measured. Recorded energy data remain unused, and manufacturers’ data differ from the real performance. For this purpose, manufacturer and real data are combined and continuously adapted to form part-load chiller models. This study applied a predictive optimization algorithm to calculate the optimal operating conditions of multiple chillers. A sprinkler tank offers the opportunity to store cold-water for later utilization. This potential is used to show the load shifting potential of the cooling system by using a variable electricity price as an input variable to the optimization. The set points from the optimization have been continuously adjusted throughout a dynamic simulation. A case study of a plastic processing company evaluates different scenarios against the status quo. Applying an optimal chiller sequencing and charging strategy of a sprinkler tank leads to electrical energy savings of up to 43%. Purchasing electricity on the EPEX SPOT market leads to additional costs savings of up to 17%. The total energy savings highly depend on the weather conditions and the prediction horizon.
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Anand, Gopalakrishnan, and Ellen Makar. "Chilled Coil Control and Field Performance for Turbine Inlet Air Chilling." International Journal of Air-Conditioning and Refrigeration 29, no. 02 (June 2021): 2150019. http://dx.doi.org/10.1142/s201013252150019x.
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Ambient conditions greatly affect the combustion turbine performance. The Absorption Refrigeration Cycle Turbine Inlet Chilling (ARCTIC) system can chill the inlet air of the turbine to maintain optimum performance at all ambient temperatures. However, turbine characteristics, bell-mouth icing concerns, economics and performance guarantees require maintaining the inlet air temperature within a narrow range throughout the year. These considerations require strict control of the Turbine Inlet Air Chilling (TIAC) coil performance over a wide range of operating conditions. This paper describes the field performance and control of the chilling coil for a Mars 100 turbine. The controls logic had been developed from previously published empirical model of the chilling coil and model of the chilling loop performance at the various ambient conditions. Since commissioning at the end of summer 2020, the ARCTIC has provided inlet air chilling over a range of ambient conditions. Typically, the inlet air is maintained at 7.2∘C (45∘F) by controlling the TIAC chilled water flow rate and temperature. On cooler days, if the inlet air temperature drops to 5.6∘C (42∘F) the chilled water pump turns OFF automatically to prevent bell-mouth icing. Thus, the chiller accommodates chilling load variations down to zero load. On colder days, the ARCTIC continues operating till the ambient temperature drops below 1.7∘C (35∘F) and then turns OFF. The chiller turns back ON when the 8 h average inlet air temperature exceeds 10∘C (50∘F). These parameters can be adjusted remotely by the operator and help maintain performance guarantees while minimizing chiller cycling. Quasi-steady state data were analyzed to quantify the chilling load and coil performance over a range of operating conditions.
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Sheff, Joey G., Morgan Hepburn, Yaping Yu, Susan P. Lees-Miller, and David C. Schriemer. "Nanospray HX-MS configuration for structural interrogation of large protein systems." Analyst 142, no. 6 (2017): 904–10. http://dx.doi.org/10.1039/c6an02707e.
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Chang, Yung-Chung, and Wu-Hsing Chen. "Optimal chilled water temperature calculation of multiple chiller systems using Hopfield neural network for saving energy." Energy 34, no. 4 (April 2009): 448–56. http://dx.doi.org/10.1016/j.energy.2008.12.010.
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Suzuki, Yuya, Misa Imazu, Jun Shinoda, Ryoya Furukawa, Yumiko Araki, Shin-ichi Tanabe, Kenji Fujino, et al. "Efficient Operation of Heat Source using High-temperature Chilled Water in an Advanced Office Building." E3S Web of Conferences 111 (2019): 03071. http://dx.doi.org/10.1051/e3sconf/201911103071.
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In recent years, energy conservation has become a major focus in the industrial sector. Many office buildings in Japan achieve energy savings by introducing highly efficient equipment and systems, such as high-temperature cooling water (14 °C), which increases heat source efficiency. However, such equipment requires adjustments to increase operational efficiency. In this case study, the efficiency of equipment using high-temperature cooling water was further improved through operation control optimization. The energy efficiency before and after the improvement was compared. The target building has chilled and hot water supplied to each floor from district heating and high-temperature chilled water supplied from cooling chillers on the rooftop. The energy consumption of two floors was evaluated: a subjective floor with equipment using high-temperature cooling water installed, and a common floor with a conventional system. After on-site verification, changes were made to the operation control of the cooling towers, condenser pumps, primary pumps, secondary pumps, and air handling units. As a result, the coefficient of performance of the water-cooled chiller and the whole system improved by 0.40 and 0.45, respectively. The flow rate of the air conditioning equipment using high-temperature cooling water decreased while maintaining an equivalent amount of heat extraction. In conclusion, the efficiency of the equipment was further improved by operation control optimization.
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Martínez, Pedro J., Pedro Martínez, Victor M. Soto, Luis A. Bujedo, and Juan Rodriguez. "Design of a 35 kW Solar Cooling Demonstration Facility for a Hotel in Spain." Applied Sciences 10, no. 2 (January 9, 2020): 496. http://dx.doi.org/10.3390/app10020496.
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Solar cooling systems have the advantage of the coincidence between the hours of cooling demand and the hours of solar radiation availability, and they can contribute to reduce the energy consumption in buildings. However, the high cost of thermal solar cooling facilities with absorption chillers, maintenance issues, legionella risk and water consumption (associated to the necessary cooling tower) have limited the use of these systems to demonstration projects. A simplified Transient System Simulation Tool (TRNSYS) model was developed to provide the owner of the demonstration facility the information he needs for design decision-making. This model was validated with experimental data registered in a solar cooling system designed and built by the authors. Different collector field surfaces, hot water storage tank volumes, and absorption machine driving temperatures were analyzed for a hotel demonstration facility. In terms of the energy delivered to the absorption chiller the optimum dimensioning corresponded to the lowest values of the driving temperature (75 °C) and specific storage volume (15 Lm2). From an economic point of view, the saving of 1515 euros per year when compared with an electric compression chiller does not compensate the investment of 3000 euros per kW of cooling capacity that cost the thermal solar cooling facility.
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KAYA, Durmus, and Hisham ALIDRISI. "Energy savings potential in air conditioners and chiller systems." TURKISH JOURNAL OF ELECTRICAL ENGINEERING & COMPUTER SCIENCES 24 (2016): 935–45. http://dx.doi.org/10.3906/elk-1311-204.
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Wing Yu, Fu, and Kwok Tai Chan. "Energy management of chiller systems by data envelopment analysis." Facilities 31, no. 3/4 (February 22, 2013): 106–18. http://dx.doi.org/10.1108/02632771311299395.
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Gibelhaus, Andrej, Thanaphum Tangkrachang, Uwe Bau, Jan Seiler, and André Bardow. "Integrated design and control of full sorption chiller systems." Energy 185 (October 2019): 409–22. http://dx.doi.org/10.1016/j.energy.2019.06.169.
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Радченко, Микола Іванович, Євген Іванович Трушляков, Сергій Анатолійович Кантор, Богдан Сергійович Портной, and Анатолій Анатолійович Зубарєв. "МЕТОД ВИЗНАЧЕННЯ ТЕПЛОВОГО НАВАНТАЖЕННЯ СИСТЕМИ КОНДИЦІЮВАННЯ ПОВІТРЯ ЗА МАКСИМАЛЬНИМ ТЕМПОМ ПРИРОЩЕННЯ ХОЛОДОПРОДУКТИВНОСТІ (на прикладі кондиціювання повітря енергетичного призначення)." Aerospace technic and technology, no. 4 (October 14, 2018): 44–48. http://dx.doi.org/10.32620/aktt.2018.4.05.
Full textAbstract:
It is justified the necessity of taking into consideration changes in thermal loads on the air conditioning system (heat and moisture treatment of air by cooling it with decreasing temperature and moisture content) in accordance with the current climatic conditions of operation. Since the effect of air cooling depends on the duration of its use and the amount of cold consumption, it is suggested that it be determined by the amount of cold spent per year for air conditioning at the GTU inlet, that is, for annual refrigerating capacity. The example of heat-using air conditioning at the inlet of a gas turbine unite (energy–efficient air conditioning systems) analyzes the annual costs of cooling for cooling ambient air to the temperature of 15 °C by an absorption lithium-bromide chiller and two-stage air cooling: to a temperature of 15 °C in an absorption lithium-bromide chiller and down to temperature 10 °С – in a refrigerant ejector chiller as the stages of a two-stage absorption-ejector chiller, depending on the installed (project) refrigerating capacity of waste heat recovery chiller.It is shown that, based on the varying rate of increment in the annual production of cold (annual refrigeration capacity) due to the change in the thermal load in accordance with current climatic conditions, it is necessary to select such a design thermal load for the air conditioning system (installed refrigeration capacity of chillers), which ensures the achievement of maximum or close to it annual production of cold at a relatively high rate of its increment. It is analyzed the dependence of the increment on the annual refrigerated capacity, relative to the installed refrigeration capacity, on the installed refrigeration capacity, in order to determine the installed refrigeration capacity, which provides the maximum rate of increase in the annual refrigerating capacity (annual production of cold). Based on the results of the research, it is proposed the method for determining the rational thermal load of the air conditioning system (installed – the design refrigeration capacity of the chiller) in accordance with the changing climatic conditions of operation during the year, which provides nearby the maximum annual production of cold at relatively high rates of its growth