Academic literature on the topic 'Non-uniform transient environments'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Non-uniform transient environments.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Non-uniform transient environments"
1
Zhang, H., C. Huizenga, E. Arens, and D. Wang. "Thermal sensation and comfort in transient non-uniform thermal environments." European Journal of Applied Physiology 92, no. 6 (2004): 728–33. http://dx.doi.org/10.1007/s00421-004-1137-y.
Full text
2
Zhang, Hui, Edward Arens, Charlie Huizenga, and Taeyoung Han. "Thermal sensation and comfort models for non-uniform and transient environments, part III: Whole-body sensation and comfort." Building and Environment 45, no. 2 (2010): 399–410. http://dx.doi.org/10.1016/j.buildenv.2009.06.020.
Full text
3
Zhang, Hui, Edward Arens, Charlie Huizenga, and Taeyoung Han. "Thermal sensation and comfort models for non-uniform and transient environments, part II: Local comfort of individual body parts." Building and Environment 45, no. 2 (2010): 389–98. http://dx.doi.org/10.1016/j.buildenv.2009.06.015.
Full text
4
Zhang, Hui, Edward Arens, Charlie Huizenga, and Taeyoung Han. "Thermal sensation and comfort models for non-uniform and transient environments: Part I: Local sensation of individual body parts." Building and Environment 45, no. 2 (2010): 380–88. http://dx.doi.org/10.1016/j.buildenv.2009.06.018.
Full text
5
Danca, Paul, Florin Bode, Angel Dogeanu, et al. "Experimental study of thermal comfort in a vehicle cabin during the summer season." E3S Web of Conferences 111 (2019): 01048. http://dx.doi.org/10.1051/e3sconf/201911101048.
Full textAbstract:
Thermal comfort evaluation for vehicle occupants is very complicated due to the transient nature and non-uniformity of the vehicle interior. The thermal sensation of an automotive occupant is affected by the surrounding environment. More than this, the actual standard is proposing three evaluation indexes and was developed for steady state and controlled conditions and some of the indexes are not adapted for this complex environment. In this article the three standardized indexes values are compared in term of thermal comfort, in a vehicle passenger in summer season. The results are showing that the mean values of PMV/PPD model calculated in a single point with Comfort Sense equipment are far from the TSV mean values which was collected in questionnaires, while the teq index which was calculated with an advanced thermal manikin are closer to the TSV comfort votes. This may be explained by the fact that the TSV and teq consider the sensation for each body part at the local level. For a correct evaluation of the thermal comfort in non-uniform and transient environments like in the vehicles, is not enough to measure in a single point and the results to be considered in all the ambiance. The main conclusion is that the PMV/PPD indexes are not very well adapted to the vehicle environment.
6
Zhao, Yin, Hui Zhang, Edward A. Arens, and Qianchuan Zhao. "Thermal sensation and comfort models for non-uniform and transient environments, part IV: Adaptive neutral setpoints and smoothed whole-body sensation model." Building and Environment 72 (February 2014): 300–308. http://dx.doi.org/10.1016/j.buildenv.2013.11.004.
Full text
7
Imai, Kenjiro, Takuya Kataoka, Takafumi MASUDA, and Tomohiro Inada. "New Evaluation Method of Transient and Non-Uniform Environment in a Passenger Compartment." SAE International Journal of Passenger Cars - Mechanical Systems 5, no. 2 (2012): 876–84. http://dx.doi.org/10.4271/2012-01-0633.
Full text
8
Chen, C. K., C. I. Hung, and H. C. Horng. "Transient Natural Convection on a Vertical Flat Plate Embedded in a High-Porosity Medium." Journal of Energy Resources Technology 109, no. 3 (1987): 112–18. http://dx.doi.org/10.1115/1.3231335.
Full textAbstract:
This paper provides an analysis of the non-Darcian effect on transient natural convection of a vertical flat plate embedded in a high-porosity medium. The plate surface is either maintained at an uniform wall temperature (UWT), or subjected to an uniform heat flux (UHF), and convective, boundary and inertia effects are considered. The local volume-averaged principles and certain empirical relations have been utilized to establish the governing equations. The coupled nonlinear partial differential equations are solved with a numerical integration technique using a cubic spline. Along with transient mean and local Nusselt numbers at the plate, representative transient velocity and temperature profiles are presented. Both effects for non-Darcian flow model are shown to be more pronounced in high-porosity medium and, hence, reduce the heat transfer rate.
9
Liu, Hao, Xia Sheng Sun, and Xiao Dong Li. "Modal Analysis of Wing Considering Transient Thermal Effects." Applied Mechanics and Materials 444-445 (October 2013): 1400–1406. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.1400.
Full textAbstract:
The severe aerodynamic heating on the surface of modern hypersonic flight vehicle, that can bring high temperature and large temperature gradients in the structure of the vehicle, will be a challenge for the vehicles design and multidisciplinary optimization. The transient thermal environment consists of high temperature and large temperature gradients will generate two important problems related to vehicle structure, namely: 1) the material property, such as elastic modulus, will be degraded at elevated temperature, and 2) the non-uniform thermal stress cased by large temperature gradients will change the stiffness distribution of wing structure, which can make the modal frequencies and shapes of structure changed remarkably. Firstly, the theory and methodology of structure modal analysis in transient thermal environment is outlined. Subsequently, the transient temperature field of structure considering aerodynamic heating is obtained by employing computational technology of aerodynamic heating/structure heat transfer coupling program. Finally, the modal frequencies and shapes of vehicle structure under transient temperature field is calculated based on finite element method (FEM). Based on the analysis and investigation of the simulation results, the influence of the transient thermal environment on structure modal frequency and shape is determined. Furthermore, the investigation of wing structure modal analysis considering aerodynamic heating is an important basis of aerothermoelastic simulation.
10
Lai, Dayi, and Qingyan Chen. "A two-dimensional model for calculating heat transfer in the human body in a transient and non-uniform thermal environment." Energy and Buildings 118 (April 2016): 114–22. http://dx.doi.org/10.1016/j.enbuild.2016.02.051.
Full textDissertations / Theses on the topic "Non-uniform transient environments"
1
El, Kadri Mohamad. "Modèle thermo-neurophysiologique du corps humain pour l'étude du confort thermique en conditions climatiques hétérogènes et instationnaires." Thesis, La Rochelle, 2020. http://www.theses.fr/2020LAROS006.
Full textAbstract:
Dans ces travaux de thèse, nous avons développé un nouveau modèle de thermorégulation du corps humain basé sur la neurophysiologie et nommé Neuro Human Thermal Model (NHTM). Il est dédié à prédire les variables physiologiques dans des environnements instationnaires et hétérogènes. De plus, ce modèle est couplé au modèle de confort thermique de Zhang pour prédire la sensation et le niveau de confort thermique des occupants dans les espaces intérieurs. Le système passif du modèle NHTM est basé sur celui du modèle de Wissler. Ce système est couplé à un système actif basé sur les signaux des thermorécepteurs. Le système passif consiste en 21 cylindres représentants les segments du corps humain. Chaque élément est divisé en 21 couches dont 15 pour les tissus et 6 pour les vêtements. Puis, chaque couche est divisée en 12 secteurs angulaires. Le modèle NHTM calcule la production de chaleur par le métabolisme, le transfert de chaleur par conduction entre les tissus et les échanges de chaleur par convection et rayonnement entre le corps et l’environnement. Le système actif calcule les mécanismes physiologiques grâce aux signaux des thermorécepteurs cutanés et centraux. Ces signaux sont calculés par le modèle de Mekjavic et Morrisson qui ont développé également le modèle de frissonnement utilisé dans le modèle NHTM. Le débit sanguin cutané est calculé par le modèle de Kingma. Par manque de données expérimentales, le modèle de sudation est basé sur l’approche du signal d’erreur des températures cutanée et centrale. Une comparaison a été effectuée entre le modèle de sudation de Wissler et celui de Fiala et al. Au vu des résultats obtenus, ce dernier a été retenu. Le modèle NHTM est en capacité de pouvoir simuler plusieurs types de populations. Pour ce faire, une analyse de sensibilité a été effectuée, grâce à la méthode de Morris, sur les paramètres des systèmes passif et actif pour déterminer les paramètres les plus influents. Ensuite, afin d’optimiser le modèle NHTM, un algorithme génétique a été utilisé pour déterminer le vecteur des paramètres qui correspond à la population des expérimentations de Munir et al. Les résultats ainsi obtenus ont été comparés aux modèles développés par différents auteurs et ont montré que le modèle NHTM est le plus performant dans la très grande majorité des cas. Le modèle NHTM a été couplé au modèle de Zhang pour pouvoir calculer la sensation et le confort thermique. Le modèle de Zhang a été choisi pour sa capacité à calculer les sensations et les niveaux de confort thermique locaux qui correspondent aux segments du corps humain dans des environnements hétérogènes. Il est aussi capable de calculer ces réponses lors des transitions thermiques. Ce modèle effectue le calcul grâce aux sorties du modèle NHTM à savoir les températures cutanées et de l’œsophage<br>In this thesis, we have developed a new thermoregulation model of the human body based on neurophysiology called Neuro Human Thermal Model (NHTM). It is dedicated to predict physiological variables in asymmetric transient environments. In addition, it is coupled with Zhang’s thermal comfort model to predict the sensation and the thermal comfort of the occupants in indoor spaces.The passive system of the NHTM model is based on that of the Wissler model. This passive system is coupled to an active system based on the signals of thermoreceptors. The passive system is segmented into 21 cylinders which represent the segments of the human body. Each element is divided into 21 layers, in which 15 for tissues and 6 for clothing. Then, each layer is divided into 12 angular sectors. The NHTM model simulates the heat production by metabolism, heat transfer by conduction within the tissues and heat exchange by convection and radiation between the body and the surrounding. The active system simulates physiological mechanisms thanks to signals of central and peripheral thermoreceptors. These signals are calculated by the model of Mekjavic and Morrisson who also developed the shivering model. The skin blood flow is calculated by the Kingma model. We could not develop a sweating model based on the signals of thermoreceptors since experimental data are not available. A comparison was made between the sweating model of Wissler and that of Fiala et al. and the last one was chosen.The NHTM model is able to simulate several types of population. This was done by a sensitivity analysis carried out, using the Morris method, on the parameters of the passive and active systems to find the most influential parameters. Then, an optimization of the NHTM model was done to determine the vector of the parameters which corresponds to the subjects of the experiments of Munir et al. using a genetic algorithm. The obtained results were compared to the models developed by several authors and showed that the NHTM model is the most efficient in most cases.The NHTM model has been coupled to the Zhang model to assess the sensation and thermal comfort. Zhang's model was chosen for its ability to assess local sensations and thermal comfort levels in non-uniform transient environments. Zhang’s model performs the calculation using the NHTM model outputs, namely the skin and esophagus temperatures
Conference papers on the topic "Non-uniform transient environments"
1
Farrington, Robert B., John P. Rugh, Desikan Bharathan, and Rick Burke. "Use of a Thermal Manikin to Evaluate Human Thermoregulatory Responses in Transient, Non-Uniform, Thermal Environments." In International Conference On Environmental Systems. SAE International, 2004. http://dx.doi.org/10.4271/2004-01-2345.
Full text
2
Al-Othmani, Mohamad, Nesreen Ghaddar, and Kamel Ghali. "Transient Human Thermal Comfort Response in Convective and Radiative Environments." In ASME 2008 Heat Transfer Summer Conference collocated with the Fluids Engineering, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/ht2008-56101.
Full textAbstract:
In this work, human transient thermal responses and comfort are studied in non-uniform radiant heating and convective heating environments. The focus was on a change from walking activity of human in outdoor cold environment at high clothing insulation to warm indoor environment at sedentary activity level associated with lower clothing insulation. A transient multi-segmented bioheat model sensitive to radiant asymmetry is used to compare how fast the human body approaches steady state thermal conditions in both radiative and convective warm environments. A space thermal model is integrated with the bioheat model to predict the transient changes in skin and core temperature of a person subject to change in metabolic rate and clothing insulation when entering conditioned indoor space. It was found that overall thermal comfort and neutrality were reached in 6.2 minutes in the radiative environment compared to 9.24 minutes in convective environment. The local thermal comfort of various body segments differed in their response to the convective system where it took more than 19 minutes for extremities to reach local comfort unlike the radiative system where thermal comfort was attained within 7 minutes.
3
Staroselsky, Alexander, Thomas J. Martin, and Luke Borkowski. "The Influence of Thermal Transient Rates on Coated Turbine Parts Life Expectancy." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-77283.
Full textAbstract:
During rapid engine throttling operations, turbine airfoils can experience very rapid heating and cooling, particularly at take-off conditions. These rapid transient events lead to the generation of high thermal gradients and non-uniform stress distributions through the thermal barrier coating, environmental barrier/bond coating and substrate. This in turn can lead to coating delamination, overheat of the substrate materials, creep and thermo-mechanical fatigue of the part. We present the process and computer modeling methodology for a physics-based prediction of deformation, damage, crack propagation and local failure modes in coated turbine airfoils and other parts operating at hot section turbine environment conditions as a function of engine operational regimes, with a particular emphasis on rapid transient events. The overall goal is to predict the effects and severity of the cooling and heating thermal rates on transient thermal mechanical fatigue life of coated hot parts (turbine airfoils, blade outer air seals and combustor liners). The computational analysis incorporates time-accurate, coupled aerothermodynamics with non-linear deformation thermal-structural finite element modeling and fracture mechanics modeling for high rate thermal transient events. Thermal barrier coating thermal failure and spallation are introduced by the use of interface fracture toughness and interface property evolution as well as dissipated energy rate. The spallation model allows estimations of the part remaining life as a function of the heating/cooling rates. Applicability of the developed model is verified using experimental coupons and calibrated against burner rig test data for high flux thermal cycles. Our results show a decrease in TBC spall life due to high rate transient events.
4
Shin, Kwangjin, Hyunjae Park, Jongsoo Kim, and Kyuil Kim. "Mathematical and Experimental Investigation of Thermal Response of an Automobile Passenger With a Ventilated Seat." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14770.
Full textAbstract:
This paper presents mathematical and experimental models developed for the prediction of thermal interactions of an automobile passenger with the cabin environment and a ventilated seat. The mathematical model developed in this work employs existing and modified human-body heat balance equations along with variable thermo-physical environmental conditions. The model predicts steady-state and transient variations of passenger skin and seat-surface temperatures with time before and after activating the seat ventilation system for the given and selected cabin air conditions and heated seat temperature. In calculating the temperature changes with time after activating the ventilated-seat system, the modified heat balance equation along with the numerical analysis using the CFD package (Fluent, v.6) has been iteratively used, in which appropriate air-side average heat transfer coefficients were determined by using the Reynolds and Nusselt analogies for various system operating conditions. An experimental chamber was built to simulate the vehicle air and seat conditions attainable during a hot summer day. A selected number of individuals have participated in the experiments. Passengers' skin and seat-surface temperatures were measured with time after activating the ventilated-seat system for various chamber conditions. Investigation of the results obtained from the mathematical model and the experimental work showed that the seat ventilation system proposed in this work is able to provide the passenger thermal comfort initiation within about 2-3 minutes after activating the seat ventilation system. It was also found that the mathematical model developed in this work needs to be improved in order to include the non-uniform chamber air and seat conditions. The additional detailed experimental works are also required to quantify the passengers' thermal responses along with various chamber conditions.
5
Safrendyo, S., and Narakorn Srinil. "Slug Flow-Induced Oscillation in Subsea Catenary Riser Experiencing VIV." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77298.
Full textAbstract:
Slug flow appearance in a multiphase-carrying riser with a long tie-back distance and deeper water is inevitable, depending on the operational and environmental conditions. Several state-of-the-art technologies in mitigating the effects of internal slug flows might not be completely effective or cost-efficient. In addition to the slug excitation, the external current flows can also affect the riser structural behavior and integrity by the presence of vortex-induced vibration (VIV). This study aims to investigate and understand the behavior of slug-conveying catenary riser under uniform and random slug excitations, in combination with VIV. The steady-state slugs are considered and modelled by a series of liquid and gas phases flowing at certain rates inside the riser pipe. Each slug unit consists of a slug liquid (oil, water or their mixture) and gas pocket. In the uniform slug flow cases, all slug units have their equal slug liquid lengths. Time-domain simulations are conducted for different slug units of 20D, 30D, 40D and 50D, where D is the pipe internal diameter, and for different internal flow rates. The non-uniform slug flow case is considered by randomly generating the time-varying slug liquid and unit lengths. Multi-frequency oscillations of the catenary riser are observed, triggered by the transient slug excitations rendering the fundamental vibration mode which is sustained over the ensuing steady-state slugging period. The random slug-induced vibration (SIV) entails larger response amplitudes which are critical from the fatigue life viewpoint, especially when VIV is also accounted for. For riser SIV analysis, only in-plane response is observed; nevertheless, the interaction of riser SIV and VIV generates both in-plane and out-of-plane responses with larger 3-D dynamic responses, deformations and stresses. Such combined SIV and VIV should be specially considered during the riser analysis and design by also taking into consideration the travelling random-like or intermittent slug flows.
6
Yang, Li, Kartikeya Tyagi, Srinath Ekkad, and Jing Ren. "Influence of Rotation on Heat Transfer in a Two-Pass Channel With Impingement Under High Reynolds Number." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42871.
Full textAbstract:
Effect of rotation on turbine blade internal cooling is an important factor in gas turbine cooling systems. In order to minimize the impact from the Coriolis force, cooling structures with less rotation-dependent cooling effectiveness are needed. This study presents an impingement design in a two pass channel to reduce impact of rotational forces on non-uniform heat transfer behavior inside these complex channels. A Transient Liquid Crystal(TLC) method was employed to obtain local heat transfer coefficient measurements in a rotating environment. The channel Reynolds number based on the channel diameter ranges from 25,000 to 100,000. The rotation number ranges from 0 to 0.14. A series of computational simulations with the SST model were also utilized to understand the flow field behavior that impacts the heat transfer distributions on the walls. A 1-D correlation of zone averaged Nusselt number distribution was derived from the measurements. Results show that rotation reduces the heat transfer on both sides of the impingement, which is due to the Coriolis force and the pressure redistribution. The local change in the present study is about 25%. Rotation significantly enhances the heat transfer near the closed end because of the centrifugal force and the ‘pumping’ effect. Within the parameters of this test, the magnitude of enhancement is 25% to 75%. Compared to U-bended two pass channel, impingement channel has advantages in the upstream channel and the end region, but performance is not beneficial on the leading side of the downstream channel.
7
Solasi, Roham, Xinyu Huang, Yue Zou, Matthew Feshler, Kenneth Reifsnider, and David Condit. "Mechanical Response of 3-Layered MEA During RH and Temperature Variation Based on Mechanical Properties Measured Under Controlled T and RH." In ASME 2006 4th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2006. http://dx.doi.org/10.1115/fuelcell2006-97094.
Full textAbstract:
Mechanical fracture of Nafion® membrane limits the life of PEM FC stacks. This is likely a result of gradual strength degradation and mechanical stress/strain transients induced by the cycling relative humidity (RH). Mechanical properties of Nafion® membrane strongly depend on water content. The objectives of the authors’ work are (1) to understand the fundamental mechanical behavior of an ionomer membrane, i.e., Nafion®, as a function of RH and (2) to develop physically meaningful models to perform stress/strain analysis of membrane electrode assemblies under RH and temperature variations. To characterize the mechanical response of an ionomer as a function of temperature and relative humidity, an environment chamber capable of generating temperatures from 25 to 100 degrees Centigrade and relative humidities from 5 to 85 percent was designed and built. An electromechanical membrane test (load) frame was mounted as an integral part of the system. An optical strain measurement device was used to record axial extension and lateral contraction of the membrane specimens without contact. Extensive mechanical tests on a commercial ionomer membrane were conducted under carefully controlled hydration and temperature. Fully nonlinear, fully anisotropic elasto-plastic constitutive representation of this ionomer material was obtained as function of temperature and RH. Water content significantly affects the elastic modulus of the membranes. Experimental data show that the elastic modulus of the membrane continuously increases up to about twice the original value during dry out. Such has been taken into account in order to accurately model the stress/strain history of the membrane during dry-out. The collected experiment data were represented in material constitutive models for use in a finite element code, ABAQUS. A 3-layer membrane electrode assembly (MEA) structure has been modeled to observe stress/strain distribution during RH and T cycling. Non-uniform electrode/membrane interfaces have been modeled as well as uniform sections to see the effects of geometric irregularities on the extreme values of stress and strain.
8
Hii, N. C., S. J. Wilcox, A. Z. S. Chong, J. Ward, and C. K. Tan. "The Application of Acoustic Emission to Monitor Pulverised Fuel Flows." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-80912.
Full textAbstract:
There are a large number of industrial processes involving the transport of pneumatically conveyed solid including mineral processing, electrical power generation, steel and cement production. For coal-fired power plant, in particular, pulverised fuel (pf) is fed by pneumatic means where coal particles are transported by the primary air from each mill directly into furnace. The distribution of coal particles to each burner bank is normally split mechanically from larger pipelines into a smaller network of pipes connected to each of the burners. Despite the use of matched outlet pipes and riffle devices within the splitters, uneven distribution of the pulverised coal inevitably occurs. Incomplete combustion due to the non-uniform distribution of the pulverised coal between the burner\u2019s feed pipes leads to a reduction in boiler efficiency. This also directly leads to an increase in slagging and fouling in the burner and increased NOx emission from the burner. Measuring can solve this problem and subsequently controlling the mass flow in each burner feed pipe and then adjusting the excess air to operate near the minimum. Over the past ten years or so, there has been increased interest in applying acoustic emission (AE) detection methods for process condition monitoring. The European Working Group for Acoustic Emission (EWGAE), 1985, defines AE as ‘the transient elastic waves resulting from local internal micro displacements in a material’. The American National Standards Institute defines AE as ‘the class of phenomena whereby transient elastic waves are generated by a rapid release of energy from a localised source or sources within a material, or the transient elastic waves so generated’. Therefore, in principle, any impulsive and energy release mechanism within a solid or on its surface, such as plastic deformation, impact, cracking, turbulence, combustion, and fluid disturbances, is capable of generating. Since these mechanisms can be associated with the degradation occurring within a particular process, it follows that AE has great potential in condition monitoring, for example, monitoring of tool wear, corrosion and process monitoring of the pneumatically conveyed solid. Unlike most of the other techniques, AE sensors are non-invasive so that their interruption with the flow within the pipe can be totally avoided. Furthermore, the frequency responses of AE sensors are normally very high (in the order of a Mega Hertz) so that they are immune to low-frequency environmental noises. The use of AE detection techniques is appropriate in this project since the frictional contacts between the flowing particles and the inner wall of the conveying pipe can effectively generate ‘elastic waves’ which propagate through the inner pipe wall and be detected by an AE sensor attached to the outer pipe wall. Consequently, the current research work aims to demonstrate the use of an AE to monitor the flow of particles in a conveying pipe. Preliminary results indicate that AE is generated and is highly repeatable for both variations in velocity for a fixed particle size and also for variations in mass flow rate at a fixed velocity.
9
Seyednezhad, Mohadeseh, and Hamidreza Najafi. "Numerical Analysis and Parametric Study of a Thermoelectric-Based Radiant Ceiling Panel for Building Cooling Applications." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23911.
Full textAbstract:
Abstract Buildings are known as one of the foremost energy consumer sectors in the world with a share of nearly 40% and hence the design and development of clean and energy efficient building energy systems is an important step towards a sustainable future. Cooling and air conditioning systems, as an essential component for occupants’ comfort, are among the largest energy end-users in buildings. Additionally, most air conditioning systems rely on using refrigerants that are harmful for the environment with considerable potential for ozone depletion and global warming. Solid-state cooling technologies that do not require refrigerant are therefore of interest to eliminate these environmental concerns. Thermoelectric (TE) modules, as a solid-state cooling technology, when supplied by DC electricity, produce a temperature gradient through the Peltier effect that can be used for cooling purposes. Due to the attractive characteristics that TE technology offers, mainly high controllability, lack of refrigerant and large moving parts, quiet operation, promising efficiency and requiring minimum maintenance required, TE-based systems are becoming an emerging technology for building cooling applications. TE-based cooling technologies have been developed and tested through integrated and non-integrated systems in the building envelope. In the present paper, the design of a TE-based radiant cooling ceiling panel is investigated through numerical modeling and parametric study. The system can be incorporated in the ceiling and will maintain a reduced ceiling temperature to provide cooling through radiation and convection for the occupants. COMSOL Multiphysics is used for modeling and simulation purposes and the performance of the system under various configurations is assessed. The effect of number and placement of TE modules for a given size of ceiling panel are investigated using several simulations in COMSOL to achieve a desired and uniform surface temperature in the minimum amount of time. The impact of incorporating various amounts of phase change material (PCM) in the ceiling panel is also assessed. PCM allows the ceiling panel to maintain the desired temperature for an extended amount of time, but it also increases the time that it takes for the panel to reach the desired temperature. Transient thermal simulations are performed for both start up and shut down scenarios and the amount of time that it takes for the ceiling temperature to cool down to the desired level (on-mode) or heat up (off-mode) to the temperature at which it has to turn back on again are calculated for various system configurations. The results from this study can be used for optimal design of TE-based radiant cooling ceiling panels to achieve high energy efficiency and low operating cost while maintaining occupants’ comfort in the buildings.