Journal articles on the topic 'Refrigeration capacity distribution'
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1
Yang, Shutong, Youlei Wang, and Yufei Wang. "Optimization of Cascade Cooling System Based on Lithium Bromide Refrigeration in the Polysilicon Industry." Processes 9, no. 9 (September 18, 2021): 1681. http://dx.doi.org/10.3390/pr9091681.
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Cascade cooling systems containing different cooling methods (e.g., air cooling, water cooling, refrigerating) are used to satisfy the cooling process of hot streams with large temperature spans. An effective cooling system can significantly save energy and costs. In a cascade cooling system, the heat load distribution between different cooling methods has great impacts on the capital cost and operation cost of the system, but the relative optimization method is not well established. In this work, a cascade cooling system containing waste heat recovery, air cooling, water cooling, absorption refrigeration, and compression refrigeration is proposed. The objective is to find the optimal heat load distribution between different cooling methods with the minimum total annual cost. Aspen Plus and MATLAB were combined to solve the established mathematical optimization model, and the genetic algorithm (GA) in MATLAB was adopted to solve the model. A case study in a polysilicon enterprise was used to illustrate the feasibility and economy of the cascade cooling system. Compared to the base case, which only includes air cooling, water cooling, and compression refrigeration, the cascade cooling system can reduce the total annual cost by USD 931,025·y−1 and save 7,800,820 kWh of electricity per year. It also can recover 3139 kW of low-grade waste heat, and generate and replace a cooling capacity of 2404 kW.
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Chen, Xinwen, Zhaohua Li, Yi Zhao, Hanying Jiang, Kun Liang, and Jingxin Chen. "Modelling of Refrigerant Distribution in an Oil-Free Refrigeration System using R134a." Energies 12, no. 24 (December 16, 2019): 4792. http://dx.doi.org/10.3390/en12244792.
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Increasing number of refrigeration units has led to an increase of CO2 emissions and the destruction of the ozone layer. Using low global warming potential (GWP) refrigerants, improving the efficiency of vapour compression refrigeration (VCR) units, and minimising refrigerant leakages can reduce the global warming effect. Investigating the refrigerant distribution under varied operating conditions can provide a deeper understanding of refrigerant charge optimization. This study proposed a model of refrigerant mass distribution in a prototype oil-free VCR system using a linear compressor with variable strokes and R134a. The absence of the oil lubricant allows the adoption of compact heat exchangers, such as micro-channels, so that the total refrigerant charge can be reduced significantly. The predicted total refrigerant charge has a Mean Absolute Percentage Error (MAPE) of 3.7%. The simulation results indicate that refrigerant distributed in the condenser is most sensitive to operating conditions and total refrigerant charges. The refrigerant accumulated in the condenser is 6.8% higher at a total refrigerant charge of 0.33 kg than that of 0.22 kg. For a total refrigerant charge of 0.33 kg, 72.1% of the total refrigerant can accumulate in the condenser. At a fixed pressure ratio, the refrigerant as a two-phase form in the condenser decreases slightly with the increase of compressor strokes, resulting in a larger mass flow rate, thus cooling capacity. The present model can be adapted for optimization of a refrigeration unit and its components.
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Hermes, Christian J. L., Joel Boeng, Diogo L. da Silva, Fernando T. Knabben, and Andrew D. Sommers. "Evaporator Frosting in Refrigerating Appliances: Fundamentals and Applications." Energies 14, no. 18 (September 21, 2021): 5991. http://dx.doi.org/10.3390/en14185991.
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Modern refrigerators are equipped with fan-supplied evaporators often tailor-made to mitigate the impacts of frost accretion, not only in terms of frost blocking, which depletes the cooling capacity and therefore the refrigerator coefficient of performance (COP), but also to allow optimal defrosting, thereby avoiding the undesired consequences of condensate retention and additional thermal loads. Evaporator design for frosting conditions can be done either empirically through trial-and-error approaches or using simulation models suitable to predict the distribution of the frost mass along the finned coil. Albeit the former is mandatory for robustness verification prior to product approval, it has been advocated that the latter speeds up the design process and reduces the costs of the engineering undertaking. Therefore, this article is aimed at summarizing the required foundations for the design of efficient evaporators and defrosting systems with minimized performance impacts due to frosting. The thermodynamics, and the heat and mass transfer principles involved in the frost nucleation, growth, and densification phenomena are presented. The thermophysical properties of frost, such as density and thermal conductivity, are discussed, and their relationship with refrigeration operating conditions are established. A first-principles model is presented to predict the growth of the frost layer on the evaporator surface as a function of geometric and operating conditions. The relation between the microscopic properties of frost and their macroscopic effects on the evaporator thermo-hydraulic performance is established and confirmed with experimental evidence. Furthermore, different defrost strategies are compared, and the concept of optimal defrost is formulated. Finally, the results are used to analyze the efficiency of the defrost operation based on the net cooling capacity of the refrigeration system for different duty cycles and evaporator geometries.
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Wang, Guiqiang, Xiaohang Cheng, Zhiqiangè Kang, and Guohui Feng. "Influence of Airflow Field on Food Freezing and Energy Consumption in Cold Storage." E3S Web of Conferences 53 (2018): 01038. http://dx.doi.org/10.1051/e3sconf/20185301038.
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Currently most food products are cooled and frozen in air-blast cold storage to prolong storage time. The airflow field distribution in storage has a great impact on the process of food freezing and energy cost by that. In this paper, a transient model of food freezing considering airflow field was developed to simulation the temperature profile of air and food products during freezing process. A lumped parameter model was used to predict the temperature and moisture profile of air, which connected all other components together, such as air coolers, food products, envelop enclosure and refrigeration system. A finite difference method was employed to model the heat transfer inside food products during freezing, where the mass transfer was neglected as the food products were wrapped with polystyrene films. Unit load factor method was applied to calculate the sensible heat refrigeration capacity and thus the total capacity of air coolers. The simulation was conducted on a large cold storage filled with large quantities of packaged food products. Results show that there are great differences in airflow field distribution at different locations in cold storage, which lead to spacial differences in freezing time required. Inappropriate set point of freezing time prolongs freezing process unnecessarily and leads to extra energy consumption. Operational mode of air coolers has a great impact on the total energy consumption, as they consume energy themselves and release equivalent heat into storage simultaneously.
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Трушляков, Євген Іванович, Андрій Миколайович Радченко, Микола Іванович Радченко, Сергій Анатолійович Кантор, and Веніамін Сергійович Ткаченко. "ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ КОНДИЦІЮВАННЯ ЗОВНІШНЬОГО ПОВІТРЯ СИСТЕМИ КОМБІНОВАНОГО ТИПУ." Aerospace technic and technology, no. 4 (August 31, 2019): 9–14. http://dx.doi.org/10.32620/aktt.2019.4.02.
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One of the most attractive reserves of enhancing the energetic efficiency of air conditioning systems is to provide the operation of refrigeration compressors in nominal or close to nominal modes by choosing rational design cooling loads (cooling capacities) and their distribution according to a cooling load behaviour within the overall design (installed) cooling load band to match current changeable climatic conditions and provide close to maximum annual cooling capacity generation according to cooling duties. The direction of increasing the efficiency of outdoor air conditioning in combined central-local type systems by rationally distributing the heat load - cooling capacity of the central air conditioner into zones of variable heat load in accordance with current climatic conditions and its relatively stable value, i.e. cooling capacity required for further air cooling at the entrance to the indoor recirculation air conditioning system is justified. By comparing the values of the excessive production of cold and its deficit within every 3 days for a rational design heat load of the air conditioning system (cooling capacity of the installed refrigeration machine), which provides close to maximum annual production of cold, and the corresponding values of the excess and deficit of cooling capacity in accordance with current climatic conditions during July substantiated the feasibility of accumulating the excess of cooling capacity of a central air conditioner at low current loads and its use for covering cooling deficit at elevated heat loads through pre-cooling the outdoor air. It is developed a scheme of a combined central-local air conditioning system, which includes the subsystems for the outdoor air conditioning in a central air conditioner and the local indoor recirculated air conditioning.
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Yang, Zongming, Mykola Radchenko, Andrii Radchenko, Dariusz Mikielewicz, and Roman Radchenko. "Gas Turbine Intake Air Hybrid Cooling Systems and a New Approach to Their Rational Designing." Energies 15, no. 4 (February 17, 2022): 1474. http://dx.doi.org/10.3390/en15041474.
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Gas turbine intake air cooling (TIAC) by exhaust gas heat recovery chillers is a general trend to improve turbine fuel efficiency at increased ambient temperatures. The high efficiency absorption lithium–bromide chillers of a simple cycle are the most widely used, but they are unable to cool inlet air lower than 15 °C. A two-stage hybrid absorption–ejector chillers were developed with absorption chiller as a high temperature stage and ejector chiller as a low temperature stage to subcool air from 15 °C to 10 °C and lower. A novel trend in TIAC by two-stage air cooling in hybrid chillers has been substantiated to provide about 50% higher annual fuel saving in temperate climate as compared with absorption cooling. A new approach to reduce practically twice design cooling capacity of absorption chiller due to its rational distribution with accumulating excessive refrigeration energy at decreased thermal loads to cover the picked demands and advanced design methodology based on it was proposed. The method behind this is issued from comparing a behavior of the characteristic curves of refrigeration energy required for TIAC with its available values according to various design cooling capacities to cover daily fluctuation of thermal loads at reduced by 15 to 20% design cooling capacity and practically maximum annual fuel reduction.
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Wang, Li Juan, Yan Feng Liu, Jia Ping Liu, and Fei Lu. "Study on a New Mathematical Model for Aggregate Air Cooling or Heating." Advanced Materials Research 374-377 (October 2011): 1882–86. http://dx.doi.org/10.4028/www.scientific.net/amr.374-377.1882.
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Before the construction of hydraulic structure, aggregate must be cooled or heated by air (we call it aggregate air cooling or heating in this paper) or other technologies to the required temperature. Previous model of aggregate air cooling or heating cannot provide the center temperature of each aggregate. So a more accurate mathematical model is developed to determine the thermal performance of aggregate, and the surface heat transfer coefficient of wet aggregate is revised. This model can predict the center temperature of an aggregate and can accurately calculate the cold down time or temperature distribution of aggregate, so that the refrigeration or heating capacity can be reasonably supplied. It’s significant for foundation engineering of hydraulic structure.
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Hamad, Mahmoud. "Magnetocaloric effect in Sr2FeMoO6/Ag composites." Processing and Application of Ceramics 9, no. 1 (2015): 11–15. http://dx.doi.org/10.2298/pac1501011h.
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The enhanced low-field magnetocaloric effect was investigated for double perovskite Sr2FeMoO6 - silver (SFMO/Ag) composites with 0, 5 and 10 wt.% of Ag. A phenomenological model was used to predict magnetocaloric properties of SFMO/Ag composites, such as magnetic entropy change, heat capacity change and relative cooling power. It was shown that magnetic entropy change (?S M) peaks of SFMO/Ag span over a wide temperature region, which can significantly improve the global efficiency of the magnetic refrigeration. Furthermore, the ?S M distribution of the SFMO/Ag composites is much more uniform than that of gadolinium. Through these results, SFMO/Ag composite has some potential application for magnetic refrigerants in an extended high-temperature range.
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DOIPHODE, PUSHPAK, MANDAR TENDOLKAR, PATRIC ANANDA BALAN, and INDRANEEL SAMANTA. "NUMERICAL ANALYSIS OF CHEST FREEZER'S CONDENSING UNIT." International Journal of Air-Conditioning and Refrigeration 22, no. 04 (December 2014): 1450028. http://dx.doi.org/10.1142/s201013251450028x.
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Chest freezers are high energy consuming refrigeration systems generally used for food storage. In a chest freezer, components such as condenser coil and fan, compressor, expansion device, etc. are placed at one corner of freezer and are covered by grills. All these components together are referred as condensing unit. Position of grills with respect to these components plays an important role in air flow distribution over condenser coil. Present work deals with the study of air flow distribution in condensing unit using Computational Fluid Dynamics (CFD) tool. Performance of the condenser is analyzed using CoilDesigner®. It is found that some air enters from side grill and bypasses the condenser coil without producing any condensing effect, resulting in degradation of performance. Effect of complete blockage of some portion of side grill on air flow distribution over condenser coil and performance of condenser is presented. Quantity of air flowing over condenser coil measured as Cubic Feet per Minute (CFM) and condenser capacity are found to be increased by approximately 10% and 2%, respectively.
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Xie, Jie Fei, Xin Hua Li, and Hong Zhang. "Study on Characteristics of the Linear Air-Conditioner Compressor at Varied Operating Conditions." Advanced Materials Research 201-203 (February 2011): 632–36. http://dx.doi.org/10.4028/www.scientific.net/amr.201-203.632.
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This paper mainly introduces a novel linear air conditioner compressor which is driven by the linear oscillatory motor with two divided moving body, of which the Cylinder-piston assembly presents symmetrical distribution along the axial direction. The compressor dynamics equations were built and solved numerically with the fourth order Runge-Kutta method. in the meantime, this paper emphatically analyzes the influence of those factors, such as the intake pressure, the exhaust pressure, the suction gas superheat, the cooling degree, on the compressor performance at varied operating conditions. These works shows that improving the suction gas pressure and reducing the exhuast pressure can help to increase the refrigeration capacity and energy efficiency ratio of the air conditioner compressor. Those analysis results provide theory foundation for design,development, and engineering application of this linear air-conditioner compressor.
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Nuriyadi, M., and Ade S. Margana. "EVALUASI DAN OPTIMASI EFISIENSI ENERGI SISTEM CHILLER DENGAN PROSES DESCALING." ROTOR 12, no. 2 (July 30, 2020): 22. http://dx.doi.org/10.19184/rotor.v12i2.18742.
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Chiller system consumes most energy (around 50%) of the electrical energy in a building. To reduce the use of energy, it is necessary to evaluate the use of energy and identify opportunities for energy savings and recommendations for increasing efficiency. The evaluation aims to ensure that a chiller system works and produces chilled water products as designed. The chiller system evaluation includes the evaluation of the chiller refrigeration system, power consumption, cooling capacity, as well as the evaluation of the piping system and pumps. Evaluation is carried out on the system before and after repairing/descaling on the chiller system.
The results of the evaluation and optimization of the chiller system are: the chilled water temperature output drops to 15oC, the cooling capacity of the chiller rises to 30 KW, the pressure of the condenser coolant pump rises to 0.58 bar. While the efficiency of the circulating pump system is 15.8%; efficiency of condenser cooling pump is 19.3% and distribution pump system efficiency is 14.1%.
Keywords: performance evaluation, optimization, chiller system.
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Masiá, Carmen, Poul Erik Jensen, Iben Lykke Petersen, and Patrizia Buldo. "Design of a Functional Pea Protein Matrix for Fermented Plant-Based Cheese." Foods 11, no. 2 (January 11, 2022): 178. http://dx.doi.org/10.3390/foods11020178.
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The production of a fermented plant-based cheese requires understanding the behavior of the selected raw material prior to fermentation. Raw material processing affects physicochemical properties of plant protein ingredients, and it determines their ability to form fermentation-induced protein gels. Moreover, the addition of oil also influences structure formation and therefore affects gel firmness. This study focuses on identifying and characterizing an optimal pea protein matrix suitable for fermentation-induced plant-based cheese. Stability and gel formation were investigated in pea protein matrices. Pea protein isolate (PPI) emulsions with 10% protein and 0, 5, 10, 15, and 20% olive oil levels were produced and further fermented with a starter culture suitable for plant matrices. Emulsion stability was evaluated through particle size, ζ-potential, and back-scattered light changes over 7 h. Gel hardness and oscillation measurements of the fermented gels were taken after 1 and 7 days of storage under refrigeration. The water-holding capacity of the gels was measured after 7 days of storage and their microstructure was visualized with confocal microscopy. Results indicate that all PPI emulsions were physically stable after 7 h. Indeed, ζ-potential did not change significantly over time in PPI emulsions, a bimodal particle size distribution was observed in all samples, and no significant variation was observed after 7 h in any of the samples. Fermentation time oscillated between 5.5 and 7 h in all samples. Higher oil content led to weaker gels and lower elastic modulus and no significant changes in gel hardness were observed over 7 days of storage under refrigeration in closed containers. Water-holding capacity increased in samples with higher olive oil content. Based on our results, an optimal pea protein matrix for fermentation-induced pea protein gels can be produced with 10% protein content and 10% olive oil levels without compromising gel hardness.
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Ding, Weihua, and Wei Chen. "Numerical Simulation of Heat Transfer Tube Characteristics of Refrigeration and Air Conditioning Based on Mixed Fractional Model." Journal of Physics: Conference Series 2074, no. 1 (November 1, 2021): 012069. http://dx.doi.org/10.1088/1742-6596/2074/1/012069.
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Abstract The main parameters affecting the heat transfer performance of heat transfer tube heat exchanges include fin shape, fin spacing, fin thickness, tube row arrangement, tube diameter, dry and wet bulb temperature and flow rate. The air side heat transfer performance of heat transfer tube heat exchange and the influence of velocity field and temperature field distribution on heat transfer effect have been the focus of domestic and foreign scholars. In this paper, based on the mixed fraction model, CFD software is used to simulate the absorption process of gravity falling film outside the heat transfer tubes of refrigeration and air conditioning, and to study the flow and heat transfer characteristics of the process. The results show that, for the heat transfer tubes with the selected structure, the heat transfer capacity increases with the increase of water flow velocity, and the heat transfer enhancement effect of turbulence is enhanced. The heat transfer tubes have better comprehensive heat transfer performance than smooth tubes with the same diameter.
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Munir, Anjum, Tallha Ashraf, Waseem Amjad, Abdul Ghafoor, Sidrah Rehman, Aman Ullah Malik, Oliver Hensel, Muhammad Sultan, and Tatiana Morosuk. "Solar-Hybrid Cold Energy Storage System Coupled with Cooling Pads Backup: A Step towards Decentralized Storage of Perishables." Energies 14, no. 22 (November 15, 2021): 7633. http://dx.doi.org/10.3390/en14227633.
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Post-harvest loss is a serious issue to address challenge of food security. A solar-grid hybrid cold storage system was developed and designed for on-farm preservation of perishables. Computational Fluid Dynamic analysis was performed to assess airflow and temperature distribution inside the cold chamber. The system comprises a 21.84 m3 cubical cold storage unit with storage capacity of 2 tonnes. A hybrid solar system comprising 4.5 kWp PV system, 5 kW hybrid inverter, and 600 Ah battery bank was used to power the entire system. A vapor-compression refrigeration system (2 tonnes) was employed coupled with three cooling pads (filled with brine solution) as thermal backup to store cooling (−4 °C to 4 °C). Potatoes were stored at 8 °C for a period of three months (May 2019 to July 2019) and the system was tested on grid utility, solar, and hybrid modes. Solar irradiation was recorded in range of 5.0–6.0 kWh/(m2 × d) and average power peak was found to be 4.0 kW. Variable frequency drive was installed with compressor to eliminate the torque load and it resulted about 9.3 A AC current used by the system with 4.6 average Coefficient of Performance of refrigeration unit. The average energy consumed by system was found to be 15 kWh with a share of 4.3 kWh from grid and 10.5 kWh from solar, translating to 30% of power consumption from grid and 70% from solar PV modules. Overall, cold storage unit efficiently controlled total weight loss (7.64%) and preserved quality attributes (3.6 ⁰Brix Total soluble solids, 0.83% Titratable acidity, 6.32 PH) of the product during storage time.
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Mao, Qianjun, Yufeng Chen, Suisui Jin, Lei Shi, and Liangli Xiao. "Experimental analysis of a continuous operating ground source heat pump system in Wuhan, China." Thermal Science 22, Suppl. 2 (2018): 491–96. http://dx.doi.org/10.2298/tsci171013261m.
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Coefficient of performance of air conditioning system is the ratio of cooling capacity and power consumption, and also is an important parameter to characterize the performance of the system. Based on an actual ground source heat pump system in Wuhan, China, this paper calculated the coefficient of performance of the system under long-term continuous cooling operation and then evaluated the performance of the system through experiment. The continuous testing time ranged from June 1, 2017, to June 15, 2017, and the outside air temperature ranged from 21?C to 32?C during the testing progress. The experimental results show that the coefficient of performance of the system changes non-linearly with time, and varies greatly with the atmospheric temperature. The results also show that the coefficient of performances average value of the system is about 3.3, and the system has good performance under refrigeration conditions. This paper helps to understand the changes in the distribution characteristics of the coefficient of performance of the ground source heat pump system and promote the wide application of the ground source heat pump system.
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Трушляков, Євген Іванович, Андрій Миколайович Радченко, Микола Іванович Радченко, Сергій Георгійович Фордуй, Сергій Анатолійович Кантор, and Богдан Сергійович Портной. "МЕТОДОЛОГІЧНІ ПІДХОДИ ДО ВИЗНАЧЕННЯ ХОЛОДОПРОДУКТИВНОСТІ СИСТЕМ КОНДИЦІЮВАННЯ ПОВІТРЯ ЗА ЗМІННИХ КЛІМАТИЧНИХ УМОВ." Aerospace technic and technology, no. 7 (August 31, 2019): 71–75. http://dx.doi.org/10.32620/aktt.2019.7.09.
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One of the most attractive reserves for improving the energy efficiency of air conditioning systems is to ensure the operation of refrigeration compressors in nominal or close to nominal modes by selecting a rational design heat load and distributing it within its design value according to the behavior of the current heat load under variable current climatic conditions to provide the maximum or close to maximum annual cooling capacity generation according to cooling duties of air conditioning. In the general case, the overall range of current thermal loads of any air conditioning system includes a range of unstable loads associated with the precooling of ambient air with significant fluctuations in cooling capacity according with current climatic conditions, and a relatively stable range of cooling capacity consumed to further reduce air temperature from a certain threshold temperature to the final outlet temperature. It is quite obvious that a stable range of heat load can be ensured within operating a conventional compressor in a mode close to the nominal mode while precooling the ambient air with significant fluctuations in heat load requires regulation of the cooling capacity through the use of a variable speed compressor. Thus, in response of the behavior of the change in current heat loads, any air conditioning system, whether the central air-conditioning system with its heat procession in a central air conditioner, or a combination thereof with a local recirculation system of indoor air, essentially consists of two subsystems: pre-cooling the ambient air and then cooling it to the set point temperature. The proposed method of distribution of design heat load depending on the behavior of the current heat load is useful for the rational design of central air conditioning systems and their combined versions with the local air conditioning system.
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Di Battista, Ruben, Maria Teresa Scelzo, and Maria Rosaria Vetrano. "Numerical Study of an Isothermal Slush Flow for Aerospace Propulsion Applications." Transactions on Aerospace Research 2019, no. 2 (June 1, 2019): 76–89. http://dx.doi.org/10.2478/tar-2019-0011.
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Abstract Slushes are two-phase solid-liquid single-species cryogenic fluids that exhibit an increased density and a greater heat capacity with respect to the corresponding normal boiling point liquids. These promising features are of large interest for applications that exploit slush as a thermal fluid, like super magnets refrigeration, cryogenic cooling of bio-materials or air conditioning, and for aerospace systems that use slush fluids as fuel or oxidizer. Several programs in the frame of the research on Slush Hydrogen (SLH2) as a new-generation fuel for aerospace propulsion have been started in the past. This work was carried out in the framework of a VKI research activity promoted by the Predict ESA Technology Research Programme, to investigate experimentally and numerically the behavior of slush flows in a representative upper stage feeding line. In this paper, we present a simulation based on a granular two-fluid model on an isothermal solid liquid mixture (slurry) and a Nitrogen slush (SLN2) fluid flowing in a horizontal pipe. A finite-volumes discretization using the software library OpenFOAM was benchmarked against experimental and numerical literature data, to assess the accuracy of the code in predicting pressure drops along the pipe axis and solid particle distribution across the pipe diameter. Moreover, the effects of concentration and inlet velocity are investigated. We show that the numerical model fairly reproduces the literature data in terms of important aspects as the solid volume fraction distribution and the pressure drops, especially for high flow rates.
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Wang, Junjing, Morane Jousse, Jitesh Jayakumar, Alejandro Fernández-Arteaga, Silvia de Lamo-Castellví, Montserrat Ferrando, and Carme Güell. "Black Soldier Fly (Hermetia illucens) Protein Concentrates as a Sustainable Source to Stabilize O/W Emulsions Produced by a Low-Energy High-Throughput Emulsification Technology." Foods 10, no. 5 (May 11, 2021): 1048. http://dx.doi.org/10.3390/foods10051048.
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There is a pressing need to extend the knowledge on the properties of insect protein fractions to boost their use in the food industry. In this study several techno-functional properties of a black soldier fly (Hermetia illucens) protein concentrate (BSFPC) obtained by solubilization and precipitation at pH 4.0–4.3 were investigated and compared with whey protein isolate (WPI), a conventional dairy protein used to stabilize food emulsions. The extraction method applied resulted in a BSFPC with a protein content of 62.44% (Kp factor 5.36) that exhibited comparable or higher values of emulsifying activity and foamability than WPI for the same concentrations, hence, showing the potential for emulsion and foam stabilization. As for the emulsifying properties, the BSFPC (1% and 2%) showed the capacity to stabilize sunflower and lemon oil-in-water emulsions (20%, 30%, and 40% oil fraction) produced by dynamic membranes of tunable pore size (DMTS). It was proved that BSFPC stabilizes sunflower oil-in-water emulsions similarly to WPI, but with a slightly wider droplet size distribution. As for time stability of the sunflower oil emulsions at 25 °C, it was seen that droplet size distribution was maintained for 1% WPI and 2% BSFPC, while for 1% BSFPC there was a slight increase. For lemon oil emulsions, BSFPC showed better emulsifying performance than WPI, which required to be prepared with a pH 7 buffer for lemon oil fractions of 40%, to balance the decrease in the pH caused by the lemon oil water soluble components. The stability of the emulsions was improved when maintained under refrigeration (4 °C) for both BSFPC and WPI. The results of this work point out the feasibility of using BSFPC to stabilize O/W emulsions using a low energy system.
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Virtue, J. G., P. D. Gee, N. M. Secomb, P. R. O'Leary, and B. P. Grear. "Facilitating feral camel removal in Australia through commercial use." Rangeland Journal 38, no. 2 (2016): 143. http://dx.doi.org/10.1071/rj15066.
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Approximately 16.5% of feral camel removal under the Australian Feral Camel Management Project (AFCMP) was by commercial means, via mustering for transport to abattoir (9.3%) and pet-meating in the field (7.2%). The challenges of commercial use of feral camels as a removal method include: variable density, mobility and distribution of the feral camel population; achieving landholder collaboration; accessibility to remote areas by road; availability of yard infrastructure and trucking capacity; and distance to slaughter facilities and end-markets. However, the AFCMP recognised commercial use as important to some Aboriginal communities, bringing a range of economic and social benefits as well as environmental outcomes in terms of reduced feral camel density. To facilitate mustering offtake, a removal assistance scheme was developed, whereby a formal landholder agreement was entered into with various legal requirements, including animal welfare. The agreement incentivised removal of both sexes: payments were for cow camels received at abattoir, but with a concurrent requirement for approximately equal sexes to be delivered to abattoir in an annual contract period. Additional project costs included contract development and oversight, landholder engagement, training and animal welfare auditing. Pet-meating, by way of ground culling and in-field butchering for meat storage in mobile refrigeration units, was also supported by the AFCMP via measures to increase harvest efficiency such as satellite tracking, aerial spotting and improved road access. However, pet-meating ceased mid-project due to changed industry demands. Post-AFCMP, mustering operations continue to service market demand for camel meat. The camel industry is also looking to camel farming to ensure greater continuity and quality of supply than can be achieved through wild harvest.
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Zherlykina, M. N., Yu A. Vorobyeva, M. S. Kononova, and S. A. Yaremenko. "Numerical Study of the Non-Azeotropic Mixture Outflow in Event Accident in the Building Cooling System." IOP Conference Series: Earth and Environmental Science 988, no. 4 (February 1, 2022): 042085. http://dx.doi.org/10.1088/1755-1315/988/4/042085.
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Abstract The range of values of the pressure of the refrigerating agent at adiabatic compression of vapors in the compressor, within which the cycle of operation of the cooling machine should be carried out, is graphically represented. The distribution of concentrations of a harmful substance – a refrigerating agent in the volume of a room in the event of depressurization of the building’s cooling supply elements is studied and the most dangerous area for human health and the critical time spent in it are determined. The amount of refrigerating agent in the system is determined depending on the cooling capacity of the outdoor unit and on the length of the freon lines, taking into account the parameters of the outdoor air. An analytical dependence is developed for determining the time of leakage of the refrigerating agent into the volume of the room, depending on the configuration of the air conditioning system and its cooling capacity. Based on the study of changes in the amount of refrigerating agent and the time of its expiration before reaching the maximum permissible concentration in the working area of the room, recommendations are presented for optimizing the parameters for monitoring the content of harmful substances in the room air, depending on the characteristics of the system.
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Nowak, Bernard, and Rafał Łuczak. "Thermal Power Of The TS-300B Refrigerator in the Aspects of Statistical Research / Moc Cieplna Chłodziarki TS-300B W Aspekcie Badań Statystycznych." Archives of Mining Sciences 60, no. 3 (September 1, 2015): 715–28. http://dx.doi.org/10.1515/amsc-2015-0047.
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Abstract The article discusses the improvement of thermal working conditions in underground mine workings, using local refrigeration systems. It considers the efficiency of air cooling with direct action air compression refrigerator of the TS-300B type. As a result of a failure to meet the required operating conditions of the aforementioned air cooling system, frequently there are discrepancies between the predicted (and thus the expected) effects of its work and the reality. Therefore, to improve the operating efficiency of this system, in terms of effective use of the evaporator cooling capacity, quality criteria were developed, which are easy in practical application. They were obtained in the form of statistical models, describing the effect of independent variables, i.e. the parameters of the inlet air to the evaporator (temperature, humidity and volumetric flow rate), as well as the parameters of the water cooling the condenser (temperature and volumetric flow rate), on the thermal power of air cooler, treated as the dependent variable. Statistical equations describing the performance of the analyzed air cooling system were determined, based on the linear and nonlinear multiple regression. The obtained functions were modified by changing the values of the coefficients in the case of linear regression, and of the coefficients and exponents in the case of non-linear regression, with the independent variables. As a result, functions were obtained, which were more convenient in practical applications. Using classical statistics methods, the quality of fitting the regression function to the experimental data was evaluated. Also, the values of the evaporator thermal power of the refrigerator, which were obtained on the basis of the measured air parameters, were compared with the calculated ones, by using the obtained regression functions. These statistical models were built on the basis of the results of measurements in different operating conditions of the TS-300B refrigerator, both on the test stand in the manufacturer’s laboratory and in the workings of underground mines. The evaluation of the measurement data distributions, as well as an analysis of the basic descriptive statistics of the mentioned variables were carried out, determining their measures of central tendency, location, dispersion and asymmetry.
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Pouraria, Hassan, and Warn-Gyu Park. "Numerical investigation on cooling performance of Ranque-Hilsch vortex tube." Thermal Science 18, no. 4 (2014): 1173–89. http://dx.doi.org/10.2298/tsci120610052p.
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A Ranque-Hilsch vortex tube (RHVT) is a mechanical device that separates a high pressure gas stream into low pressure hot and cold streams. In this study, four different two equation turbulence models namely the standard k-?, RNG k-?, Realizable k-? and standard k-? models were compared to identify the appropriate turbulence model for studying the energy separation effect in a RHVT. Comparison between the numerical and experimental results indicates that the standard k-? model is better than other models in predicting the energy separation phenomenon. The distributions of temperature, pressure, and components of velocity have been obtained in order to understand the flow behavior inside the tube. The effect of cold outlet diameter on temperature drop and refrigeration capacity was studied. The effect of cold mass fraction on the movement of stagnation point and refrigeration capacity has been investigated. Moreover, the feasibility of improving the cooling performance of vortex tube using the cooling system was investigated. The present numerical results revealed that using the cooling system, the net energy transfer rate from cold inner region to the hot peripheral region increases, thereby improving the cooling performance of the device.
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Sun, Yu, Rijing Zhao, Siyuan Wu, and Dong Huang. "Proposal, Robustness Analysis and Equivalent Implementation of Optimization Method for Row-By-Row Fin Distribution in Multi-Row Frosting Evaporator." Energies 14, no. 19 (September 23, 2021): 6069. http://dx.doi.org/10.3390/en14196069.
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The evaporator in a frost-free refrigerator typically has more tube rows, but frost deposition reduces along the airflow direction. Correspondingly, the evaporator fin distribution is thinner in the upstream rows but denser downstream, and a good match between frost and fin distribution is achieved to recover evaporator capacity loss. However, quantitative design principles of non-uniform fin distribution are lacking. A quasi-static frosting evaporator model is established and experimentally verified considering a three-dimensional (3D) evaporator, 1D frost growth and 1D non-uniform fin distribution. An optimization method for row-by-row fin distribution of a multi-row frosting evaporator is proposed based on the air pressure drop’s increase rate. When the increase rate in the air pressure drop of each row is almost equal, the smallest overall evaporator pressure drop is obtained, leading to the highest air flowrate and the greatest evaporator capacity. By applying the method, the air flowrate and the evaporator capacity increase by 5.5% and 4.6%, respectively, compared to the original fin distribution scheme. Moreover, the robustness of the optimization method is validated under wide temperature and humidity operating conditions. An equivalent implementation under an initial no-frost condition is also proposed to facilitate the optimization method without calculating the whole frosting process.
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Wan, Fubin, Xun Chen, Zhenhua Jiang, and Yinong Wu. "Effect of Thermal Cycling on Operational Characteristics and Lifetime Prediction of Space Pulse Tube Refrigerator." Mathematical Problems in Engineering 2019 (September 29, 2019): 1–15. http://dx.doi.org/10.1155/2019/6410704.
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This paper presents the operation status and results of ground thermal cycling test of pulse tube refrigerators (PTRs) for space application. Firstly, a thermal cycling degradation model was proposed by considering two physical mechanisms: contamination and fatigue damage. Then, a thermal cycling test scheme of two types of PTRs was designed and performed to demonstrate their long lifetime and high thermal stability. Two type A PTRs with cooling capacity of 1W@60 K and two type B PTRs with cooling capacity of 5W@80 K were continuously operated for about two years in a simulated vacuum thermal cycling environment. Effects of heat rejection temperature variation on thermal stability and dynamic performance of the PTRs were investigated. Furthermore, the thermal cycling degradation model was validated with the actual thermal cycling test data. Finally, the predicted pseudo-failure lifetime was acquired via experimental data and degradation model. Moreover, the estimated reliability of PTRs was obtained through using the Weibull distribution. The proposed thermal cycling test scheme and innovative lifetime prediction and reliability estimation method provide a quick and accurate approach for the cooler manufacturer to assess the lifetime and reliability of the space PTRs.
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Kadam, Anuja T., Rahul L. Jadhav, Pradnya B. Salunke, and Satwashila S, Kadam. "DESIGN AND EVALUATION OF MODIFIED CHITOSAN BASED IN SITU GEL FOR OCULAR DRUG DELIVERY." International Journal of Pharmacy and Pharmaceutical Sciences 9, no. 10 (November 1, 2017): 87. http://dx.doi.org/10.22159/ijpps.2017v9i11.20938.
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Objective: The object of the present study was to formulate and evaluate in-situ gel of modified chitosan by using temperature triggered method to improve bioavailability.Methods: Modified chitosan-based moxifloxacin HCl was prepared by cold method. polaxomer 407 adding in distilled water and this solution kept in the refrigerator. Modified chitosan and moxifloxacin HCl was dissolved separately in distilled water and added to the polymeric solution with continuous stirring until thoroughly mixed. Prepared formulation was evaluated for drug content, gelling capacity, rheological study, in vitro drug release behavior, measurement of phase change temperature, antibacterial study, release kinetics, statistical analysis.Results: The prepared formulations were evaluated for their, drug content, gelation temperature, in vitro drug release studies, rheological study and release kinetics. All batches of in situ formulations had satisfactory pH ranging from 6.2±0.2, drug content between 98.8±0.2 showing uniform distribution of drug. As the concentration of each polymeric component was increased, there was a decrease in phase change temperature. The in vitro drug release decreased with increase in polymeric concentrations. The antibacterial efficiency of the selected formulation against staphylococcus aureus confirmed that designed formulation has prolonged effect and retained its properties against bacterial infection.Conclusion: The prepared in situ gelling formulation had the appropriate combination of polaxomer 407 and modified chitosan were suitable satisfactorily sustained the drug release from moxifloxacin HCl in situ gel. The prepared formulation of moxifloxacin HCl appears to be promising drug delivery for bacterial infectious disease.
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SKRYPNYK, S. "Study of the influence of overvoltage on the quality of electricity in energy systems." Journal of Electrical and power engineering 23, no. 2 (December 23, 2020): 52–58. http://dx.doi.org/10.31474/2074-2630-2020-2-52-58.
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Our world with its high technologies has long been deeply dependent on the quality of electricity supply. In most countries of the world there are national power grids that combine the entire set of generating capacity and loads. This network provides the operation of household appliances, lighting, heating, refrigeration, air conditioning and transport, as well as the functioning of the state apparatus, industry, finance, trade, health services and utilities across the country. Without this utility, namely electricity, the modern world simply could not live at its current pace. Sophisticated technological improvements are firmly rooted in our lives and workplaces, and with the advent of e-commerce began the process of continuous transformation of the way individuals interact with the rest of the world. But with the achievement of intelligent technologies, an uninterrupted power supply is required, the parameters of which exactly meet the established standards. These standards maintain our energy security and create a reliable power system, that is maintaining the system in a trouble-free state. Overvoltage is the deviation of the rated voltage from the value of the corresponding quality standard (frequency, sinusoidal voltage and compliance of harmonics). Overvoltage in terms of fire hazard is one of the most dangerous emergency modes of electrical equipment, which causes conditions that in most cases are sufficient for the occurrence of fire hazards (exceeding the allowable voltage leads to disruption of normal operation or possible ignition). Against the background of deteriorating engineering systems, increased power consumption and poor maintenance, power supply of electrical installations, the main causes of overvoltage in electrical networks are thunderstorms (atmospheric overvoltage), switching switches, uneven phase load in electrical networks, etc. The physical picture of internal overvoltage is due to oscillatory transients from the initial to the established voltage distributions in the conductive sections due to the different situation in the electrical circuit. In the conditions of operation of electric networks planned, mode or emergency situations are possible. Therefore, the ranges of overvoltage are determined by the range from several hundred volts to tens and hundreds of kilovolts, and depend on the types of overvoltage. Atmospheric overvoltage is considered to be one of the most dangerous types of emergency modes of operation of the electrical network. This overvoltage occurs as a result of lightning discharge during precipitation by concentrating electricity on the surface of the object, the introduction of potential through engineering networks and
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Correia, L. F. L., C. G. Espírito-Santo, R. F. Braga, V. L. Brair, C. J. C. de Paula, A. A. da Silva, F. Z. Brandão, V. J. F. Freitas, R. Ungerfeld, and J. M. G. Souza-Fabjan. "34 Cellular effects of antifreeze proteins type I and III in extender for sheep semen cryopreservation." Reproduction, Fertility and Development 33, no. 2 (2021): 124. http://dx.doi.org/10.1071/rdv33n2ab34.
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Antifreeze proteins (AFP) have been included in extenders for sperm cryopreservation to prevent ice crystal formation. Thus, this study assessed the effects of supplementing semen extender with two concentrations of AFP types I and III on the quality of frozen–thawed ram sperm. The hypothesis is that various types and concentrations of AFP enhance cryopreservation of ram sperm. Semen was collected from 4 rams, pooled in 6 replicates, and allocated into 1 of 5 treatments: Control (CONT, without AFP); AFP type I [0.1 (AFPI-0.1) or 0.5 (AFPI-0.5) µg±mL−1]; or AFP type III [0.1 (AFPIII-0.1) or 0.5 (AFPIII-0.5) µg±mL−1]. Straws were placed on a metal wire net frame at 37°C and placed in a refrigerator for 2h to cool them to 5°C (−0.25°C/min). After 2h for stabilisation, straws were cooled in liquid nitrogen vapor (−15.3°C/min) and subsequently immersed (−196°C). After thawing, samples from each treatment were evaluated microscopically (sperm kinetics, plasma membrane integrity, capacitation, hypoosmotic test, acrosome status and mitochondrial activity, chromatin condensation, morphology, binding to egg perivitelline membrane, and lipoperoxidation quantification). The normal distribution of residuals was determined by Shapiro-Wilk test and homoscedasticity by Levene’s test. Normally distributed variables were analysed with one-way analysis of variance (ANOVA), followed by Tukey’s test. The non-normally distributed were analysed by Kruskal–Wallis and Dunn’s test. The repeated-measures ANOVA in general linear model (GLM) was used to effects of concentration for each AFP type in paired samples. The Greenhouse-Geisser test was applied when sphericity was not considered, followed by the Sidak test. Values of P<0.05 were considered significant. Treatments affected (P<0.05) kinetic parameters, plasma membrane integrity, and morphology. Linearity was greater in AFPI-0.1 (56.6±3.1%, mean±s.e.m.), AFPI-0.5 (56.9±2.2%), and AFPIII-0.5 (64.7±6.2%) than in CONT (36.8±3.0%). Straightness was greater in all AFP-supplemented extenders (overall mean, 78.6±2.8%) than in CONT (63.2±0.8%). Plasma membrane integrity was greater in AFPI-0.1 (49.1±4.6%) and AFPI-0.5 (36.6±7.3%) compared with CONT (13.0±4.4%). All AFP groups had a greater percentage of normal sperm (overall mean: 74.3±1.3%) than CONT (65.3±1.9%). There were no significant differences in percentage of sperm with functional membrane (overall mean: 16.1±3.3%), normal acrosome (11.5±4.5%), mitochondrial activity (24.5±6.5%), chromatin condensation (98.8±0.4%), perivitelline membrane binding rate (194.0±44.5 sperm/mm2), and lipoperoxidation (556.7±20.5 TBARS ng±mL−1). In conclusion, the use of AFP, predominantly type I, had potential as a cryoprotectant for ram sperm, increasing sperm cell protection, with no adverse effects on potential fertilization capacity and did not increase reactive oxygen species. This research was funded by FAPERJ, CNPq, and CAPES (Finance Code 001).
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Correia, L. F. L., C. G. Espírito-Santo, R. F. Braga, V. L. Brair, C. J. C. de Paula, A. A. da Silva, F. Z. Brandão, V. J. F. Freitas, R. Ungerfeld, and J. M. G. Souza-Fabjan. "34 Cellular effects of antifreeze proteins type I and III in extender for sheep semen cryopreservation." Reproduction, Fertility and Development 33, no. 2 (2021): 124. http://dx.doi.org/10.1071/rdv33n2ab34.
Full textAbstract:
Antifreeze proteins (AFP) have been included in extenders for sperm cryopreservation to prevent ice crystal formation. Thus, this study assessed the effects of supplementing semen extender with two concentrations of AFP types I and III on the quality of frozen–thawed ram sperm. The hypothesis is that various types and concentrations of AFP enhance cryopreservation of ram sperm. Semen was collected from 4 rams, pooled in 6 replicates, and allocated into 1 of 5 treatments: Control (CONT, without AFP); AFP type I [0.1 (AFPI-0.1) or 0.5 (AFPI-0.5) µg±mL−1]; or AFP type III [0.1 (AFPIII-0.1) or 0.5 (AFPIII-0.5) µg±mL−1]. Straws were placed on a metal wire net frame at 37°C and placed in a refrigerator for 2h to cool them to 5°C (−0.25°C/min). After 2h for stabilisation, straws were cooled in liquid nitrogen vapor (−15.3°C/min) and subsequently immersed (−196°C). After thawing, samples from each treatment were evaluated microscopically (sperm kinetics, plasma membrane integrity, capacitation, hypoosmotic test, acrosome status and mitochondrial activity, chromatin condensation, morphology, binding to egg perivitelline membrane, and lipoperoxidation quantification). The normal distribution of residuals was determined by Shapiro-Wilk test and homoscedasticity by Levene’s test. Normally distributed variables were analysed with one-way analysis of variance (ANOVA), followed by Tukey’s test. The non-normally distributed were analysed by Kruskal–Wallis and Dunn’s test. The repeated-measures ANOVA in general linear model (GLM) was used to effects of concentration for each AFP type in paired samples. The Greenhouse-Geisser test was applied when sphericity was not considered, followed by the Sidak test. Values of P<0.05 were considered significant. Treatments affected (P<0.05) kinetic parameters, plasma membrane integrity, and morphology. Linearity was greater in AFPI-0.1 (56.6±3.1%, mean±s.e.m.), AFPI-0.5 (56.9±2.2%), and AFPIII-0.5 (64.7±6.2%) than in CONT (36.8±3.0%). Straightness was greater in all AFP-supplemented extenders (overall mean, 78.6±2.8%) than in CONT (63.2±0.8%). Plasma membrane integrity was greater in AFPI-0.1 (49.1±4.6%) and AFPI-0.5 (36.6±7.3%) compared with CONT (13.0±4.4%). All AFP groups had a greater percentage of normal sperm (overall mean: 74.3±1.3%) than CONT (65.3±1.9%). There were no significant differences in percentage of sperm with functional membrane (overall mean: 16.1±3.3%), normal acrosome (11.5±4.5%), mitochondrial activity (24.5±6.5%), chromatin condensation (98.8±0.4%), perivitelline membrane binding rate (194.0±44.5 sperm/mm2), and lipoperoxidation (556.7±20.5 TBARS ng±mL−1). In conclusion, the use of AFP, predominantly type I, had potential as a cryoprotectant for ram sperm, increasing sperm cell protection, with no adverse effects on potential fertilization capacity and did not increase reactive oxygen species. This research was funded by FAPERJ, CNPq, and CAPES (Finance Code 001).
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Chen, Lingen, Fankai Meng, Yanlin Ge, and Huijun Feng. "Performance Optimization for a Multielement Thermoelectric Refrigerator with Linear Phenomenological Heat Transfer Law." Journal of Non-Equilibrium Thermodynamics, December 11, 2020. http://dx.doi.org/10.1515/jnet-2020-0050.
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AbstractA model of a multielement thermoelectric refrigerator with another linear heat transfer law, the linear phenomenological heat transfer law Q\propto \Delta (1/T), is established. The refrigerating capacity and coefficient of performance (COP) are analyzed and optimized. The junction temperature solution equations are derived. The optimum electrical currents and thermal conductance allocation are discussed. The influences of thermoelectric element quantity and refrigerating temperature difference on the optimum performances and optimum electrical currents are analyzed. The results show that different optimization objectives have different requirements for the distribution of electrical current and thermal conductance. The refrigeration capacity is not proportional to the number of thermoelectric elements. It is found that the refrigerating capacity can be achieved only when the number of thermoelectric elements is matched for fixed external heat exchangers. The input electrical current and the allocation of the thermal conductance between the two heat exchangers can be optimized synchronously to achieve maximum refrigerating capacity or maximum COP. Performance is compared with that with a Newtonian heat transfer law. The influences of the Thomson effect are also examined. Performance of the refrigerator with Newtonian heat transfer law is higher than that of the refrigerator with linear phenomenological heat transfer law. The Thomson effect can improve the performance of the refrigerator.
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Panda, Debashis, Suraj Kumar Behera, Ashok Kumar Satapathy, and Sunil K. Sarangi. "Thermodynamic characteristics of a single stage pneumatically driven Gifford-McMahon refrigerator." Journal of Thermal Science and Engineering Applications, April 7, 2022, 1–24. http://dx.doi.org/10.1115/1.4054284.
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Abstract At present, the demand of high cooling capacity Gifford-McMahon (GM) refrigerators is increasing to cool the high-temperature superconducting magnets in cryogenic temperature range. Therefore, it is necessary to enhance the cooling capacity of existing refrigerators, which needs a thorough understanding of related thermodynamic phenomena. In this paper, thermodynamic processes of a GM refrigerator are analyzed and its performance is compared with Carnot cycle, and Brayton cycle with and without work recovery. Subsequently, a mathematical model has been formulated for a pneumatically-driven GM refrigerator by applying the fundamental principles of thermodynamics and mechanics. The model computes the influence of geometrical and operating parameters upon its refrigeration performance. Subsequently, the impact of valve opening intervals upon internal thermodynamic and dynamic processes is evaluated. The dynamic characteristics of the displacer motion, transient variation of mass flow, and pressure distribution are studied by the model for different values of idling angles. It is found that an increase in the idling angle of the refrigerator, reduces its cooling capacity. An experimental study has also been undertaken to corroborate the mathematical results.
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Concepción-Brindis, Andrés, Edgar Iván Jiménez-Ruiz, Javier Germán Rodríguez-Carpena, María Teresa Sumaya-Martínez, Leticia Mónica Sánchez-Herrera, Viridiana Peraza-Gómez, Nathaly Montoya-Camacho, and Víctor Manuel Ocaño-Higuera. "ANTIOXIDANT CAPACITY AND OXIDATIVE STABILITY OF AN AVOCADO BY-PRODUCT PASTE WITH AND WITHOUT SEED." Agrociencia, May 17, 2022. http://dx.doi.org/10.47163/agrociencia.v56i3.2801.
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During the harvest, processing, and distribution of avocado (Persea americana Mill.), a large amount of waste (peel, seed, and pulp) is produced, which has proven to have antioxidant properties and this by-product might be used as input within the food production chain. This study evaluates the lipid oxidation, antioxidant capacity and phenolic compounds of two pastes made with avocado by-products (with seed: PS and without seed: PWS) during 60 d stored under refrigeration. On the results obtained, an analysis of variance (ANOVA) was performed, followed by the Tukey’s test (p ≤ 0.05). The lipid oxidation was controlled in both pastes and was even reduced during storage. In the PS, the antioxidant capacity declined, although it remained high and very similar to the PWS towards the end of the storage. The concentration of phenolic acids increased during most of the time of storage. Although PWS displayed better results with two of the analyses performed, both pastes were considered to have important antioxidant characteristics, which remained during the refrigerated storage. Due to this, its potential use in the production of foods is inferred, particularly for animals such as cattle, pigs, in aquaculture, or even in the cosmetics industry.
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Baiju, V., and C. Muraleedharan. "Experimental Analysis on Adsorption Characteristics of Methanol and R134A by Activated Carbon in Adsorption Refrigeration System." Journal of Thermal Science and Engineering Applications 7, no. 1 (October 28, 2014). http://dx.doi.org/10.1115/1.4028548.
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This paper presents adsorption and desorption characteristics of two different working pairs—activated carbon–methanol and activated carbon–R134a—determined experimentally. Dubinin–Radushkevich (D–R) equation is used to correlate the adsorption isotherms and to form the pressure, temperature, and concentration diagrams for both the assorted working pairs. The results show that the maximum adsorption capacity of activated carbon–R134a working pair is 1.21 times that of activated carbon–methanol. Temperature and pressure distribution throughout the adsorbent bed and their variation with adsorption time are also predicted. Use of artificial neural network (ANN) is proposed to determine the uptake from measured pressure and temperature. The back propagation algorithm with three different variants, namely, scaled conjugate gradient (SCG), Pola–Ribiere conjugate gradient (CGP), and Levenberg–Marquardt (LM) and logistic sigmoid transfer function are used, so that the best approach could be found out. After training, it is found that LM algorithm with 11 neurons is the most suitable for modeling adsorption refrigeration system. The adsorption and desorption uptake obtained experimentally are compared with the uptake predicted by D–R equation and ANN modeling.
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Banos, Oscar, Ute Bergmann, Maja Glorius, Sven Ohmann, Torsten Seidel, and Cornelia Breitkopf. "New preparation methods for coated heat exchangers in adsorption refrigeration and heat pumps applications." Scientific Reports 12, no. 1 (May 14, 2022). http://dx.doi.org/10.1038/s41598-022-11548-3.
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AbstractAdsorption refrigeration systems and heat pumps still possess a relatively reduced market share as compared to the traditional compression systems. Despite having the great advantage of being powered by cheap heat (instead of expensive electric work), the implementation of systems based on adsorption principles remains limited to few specific applications. The main drawback that needs to be solved is their reduced specific power due to the low thermal conductivity and low stability of the adsorbents. The current state of the art of commercial adsorption cooling systems rely on adsorbers based on coated finned heat exchangers to optimize the cooling power. It is a well known result, that the reduction of the thickness of the coating derives in a reduction of the mass transport impedance, and that the increment of the ratio surface to volume of conductive structures increases the power without reducing the efficiency. The metallic fibres used in this work can offer a ratio of specific surface in the range of 2500–50,000 m2/m3.Three methods of preparing very thin but stable salt-hydrate coatings on metallic surfaces, including metallic fibres, for the production of coated heat exchangers with high specific power, are presented for the first time. A surface treatment based on aluminium anodizing was chosen to create a stronger bond between coat and substrate. The microscopic structure of the resulting surface was analysed by Scan Electron Microscopy. To verify the presence of the desired species Attenuated Total Reflectance-Fourier Transformed Infrared and Energy dispersive X-ray spectroscopy were employed in the analysis. Their capacity to form hydrates was verified via simultaneous Thermogravimetric Analysis (TGA)/Differential Thermogravimetry (DTG). Over a mass difference of 0.07 g(water)/g(composite) was detected in the coating of MgSO4, which showed signs of dehydration at temperatures around 60 °C, and repeatability after rehydration. Also positive results were obtained with SrCl2 and ZnSO4 with mass differences around 0.02 g/g below 100 °C. Hydroxyethyl Cellulose was chosen as additive to increase the stability and adherence of the coatings. The adsorption properties of the product were evaluated with simultaneous TGA-DTG, while their adherence was characterized by means of a procedure based on the test described in ISO2409. Coatings of CaCl2 displayed a much improved consistency and adherence, while retaining its adsorption capacity, showing mass differences of around 0.1 g/g at temperatures below 100 °C. Also MgSO4 retains the capacity of forming hydrates, showing a mass difference of more than 0.04 g/g below 100 °C. Finally, coated metallic fibres were investigated. Results show that the effective heat conductivity of a fibre structure coated with Al2(SO4)3 can be up to 4.7 times higher as compared to a block of pure Al2(SO4)3 . The coverage of the pursued coatings was visually investigated and the internal structure was evaluated by microscopic imaging of cross-sections. Coatings of around 50 µm of Al2(SO4)3 were generated, but in general the process requires optimization to achieve a more uniform distribution.
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Goswami, Tridib Kumar. "Role of Cryogenics in Food Processing and Preservation." International Journal of Food Engineering 6, no. 1 (January 13, 2010). http://dx.doi.org/10.2202/1556-3758.1771.
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Food materials are perishable by nature. They require processing or preservation techniques to enhance the storage life. Cryogenics is a branch of engineering wherein production of cryogen and the maintenance of low temperature technologies are studied. One such cryogen, liquid nitrogen (LN2) has a tremendous potential to be used as a total loss refrigerant. In this paper, the different aspects of the utilization of LN2 as a refrigerant and as a gas are discussed in details.In freezing for individual quick freezing LN2 can be used as a refrigerant to get an ultra rapid freezing. Due to its rapidity LN2 freezing is capable of producing small ice crystals in size and there by helps immensely in retaining quality reducing substantial amount of drip loss.LN2 has gained tremendous popularity for the transportation of frozen foods. Apart from the intermittent spraying of LN2, dump charging method has been also developed wherein the refrigerant required for a point to point transportation is supplied to a frozen cargo before the commencement of the journey eliminating the requirement of LN2 vessel to be taken on board.Grinding is a technique which reduces the size of spices, considerably increasing the surface area available to impart flavor to any prepared food. Unfortunately, a substantial amount of flavoring compounds is lost due to the increase in temperature while using conventional grinding methods. LN2 can act as a rescuer for retention of quality by reducing the spice as well as grinder temperature substantially. Experimental analysis reveals that the loss of volatile component and particle size distribution of the ground spices are more than the satisfaction level of the processor.LN2 has the capacity to both lower the temperature and flush off the inside air of a closed container. This serves a dual purpose: The temperature of the closed chamber is brought to the desired level almost instantaneously and the gas compost ion can be changed immediately. The application of LN2 helps to minimize the need for high-capacity refrigeration system. Only 10% of the installation capacity is required for maintaining the desired temperature.
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Yulianti, Anni, and Endang Indriasih. "Pendanaan Program Imunisasi Dasar di 71 Kabupaten/Kota di Indonesia Tahun 2013-2014." Jurnal Penelitian dan Pengembangan Pelayanan Kesehatan, October 23, 2018, 121–32. http://dx.doi.org/10.22435/jpppk.v2i2.128.
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Abstrak
Imunisasi adalah suatu intervensi kesehatan yang hemat biaya dan efektif untuk mencegah penderitaan akibat penyakit, kelumpuhan dan kematian. Dukungan pendanaan diharapkan mampu meningkatkan cakupan Imunisasi Dasar Lengkap (IDL).Tulisan ini merupakan hasil analisis data Riset Pembiayaan Kesehatan (RPK) di Era Jaminan Kesehatan Nasional (JKN) Tahun 2015. Metode District Health Account (DHA) digunakan untuk menghitung pendanaan program imunisasi dasar di kabupaten/kota pada tahun 2013-2014 menurut sumber dan alokasi anggaran. Hasil analisis menunjukkan anggaran imunisasi dasar di 71 kabupaten/kota berkisar 0,10%–2,3% dari APBD Kesehatan Tahun 2013, dengan disparitas yang cukup lebar. Sumber utama pendanaan program imunisasi di kabupaten/kota adalah PAD, DAU, dekonsentrasi (Dekon) dan BOK atau masih tergantung dari dana transfer pusat. Pendanaan imunisasi nasional pada tahun 2014 meningkat secara bermakna mencapai sekitar 2,6 kali lipat dari tahun 2013. Pendanaan program imunisasi sekitar 90% didanai dari APBN, sisanya dari donor (terbesar dari GAVI). Komponen terbesar alokasi secara nasional adalah untuk pengadaan vaksin, pengenalan vaksin baru dan investasi. Sementara alokasi di kabupaten/kota (dana pendamping) sebagian besar dimanfaatkan untuk kegiatan pelayanan dan kurang dari 8% untuk surveilans dan pelatihan. Daerah dengan kapasitas fiskal tinggi tidak berarti memiliki anggaran imunisasi yang besar atau cakupan IDL yang tinggi. Direkomendasikan untuk mempertahankan kebijakan pendanaan imunisasi yang berbiaya tinggi (vaksin, kulkas vaksin, cold room) bersifat sentralistik dari APBN, sedangkan provinsi dan kabupaten/kota menyediakan anggaran untuk pelatihan, distribusi, vaksin carier beserta bahan habis pakai dan injection kit. Perlu crash program khusus dengan tambahan dana pendamping (operasional) dari APBN bagi kabupaten/kota yang tidak pernah berhasil mencapai IDL 80%. Perlu dikembangkan alternatif sumber pembiayaan untuk pendanaan imunisasi di kabupaten/kota, misalnya melalui dana kapitasi dan sektor swasta. Puskesmas harus memperbaiki dan meningkatkan kemampuan perencanaan dan belanja anggaran imunisasi yang efektif.
Kata kunci: imunisasi, pembiayaan, District Health Account
Abstract
Immunization is an effective and efficient health intervention to prevent severe illness, disability and child deaths. Funding support is important in order to achieve targeted universal child immunization (UCI) at high coverage. An Analysis of 2015’s National Survey on Health Financing in the Implementation of National Health Insurance (JKN) was conducted by using District Health Account method to figure out the sources and budget allocation on routine immunization programs in 71 districts / cities in 2013-2014. The results shows that the routine Immunization budget varies from 0.10% to 2.3% of the 2013 APBD (district budget), with a wide disparity. The main sources of funding for immunization programs in districts/cities are PAD, DAU, Dekon and BOK, which were still depend on central transfer funds (APBN). National immunization funding in 2014 increased significantly by 2.6x from 2013. Sources for the routine immunization program was around 90% funded by APBN (central budget), the rest from donors (GAVI, WHO, Unicef). At national level, funding allocation was mostly for vaccines procurement, introduction of new vaccines and investments. While, allocations in districts / cities was mostly used for service delivery and less than 8% for surveillance and training. District/city with high fiscal capacity doesn’t significantly having a large immunization budget or high coverage. It is recommended to maintain centralistic mechanism on immunization funding for high-cost components (vaccine, vaccine refrigerator, cold room) by APBN; while the Province and District / City provide a budget for training, distribution, vaccines carrier along with consumables gods and injection kits adjusted by fiscal capacity and service demands. Special crash programs need to carry out with additional accompaniment fund source from the provincial or district budget for targeted areas which never reached 80% coverage. Other funding resources should be widely explored to examine alternatives budget, such as capitation (JKN), private fund. Puskesmas competency also should be improved on budget planning and effective purchasing.
Keywords: immunization, financing, District Health Account