Theoretical study of thermoelectric cooling system performance

This work provides a theoretical investigation to study the effect of different operational parameters on theperformance of TE cooling system including the system COP and the rate of heat transfer. The parametersinvestigated are, the applied input power, inlet working fluid velocity, the arrangement of utilized TECs modules andfluid type. The geometry is created with ANSYS multi-physics software as a two-dimensional base case, it isconsisted from two attached horizontal ducts of length (520 mm) and (560 mm), the interface surface between the twoducts contains three thermoelectric modules (4 mm height by 40 mm wide and 40 mm length). The distance betweentwo consecutive thermoelectric modules (150 mm), the inlet and outlet duct diameter (15 mm) and the height of eachduct (10 cm), the inlet voltage to thermoelectric modules ranges from 8.0 V to 12 V and the water inlet velocity to thetwo ducts from 0.001 to 0.01 m/s. Theoretical results showed that the overall COP of TE cooling system is increasedwith the applied input power up to 8.0 W then it decreases with input power up to 18 W after that it takes nearly aconstant value, a noticeable enhancement in the COP is found when the three TECs are in use (Case 10) and the COPof TE cooling system using pure water and nanofluid with 0.05% of nanoparticles as coolants takes the maximumvalue

CFD Modeling of Thermoelectric Air Duct System for Cooling of Building Envelope

A multi-stage of thermoelectric modules is used in an air duct as a cooling system. The ThermoElectric Air Duct (TE-AD) system is installed with 24 ThermoElectric Modules (TEMs) installed with heat sink, cold plate and exhaust fan for air circulation. To simplify the TE-AD system, a three-dimensional model is proposed and implemented in a Computational Fluid Dynamics (CFD) simulation environment (FLUENT). An analysis of results, obtained in the experimental study of the TE-AD system for cooling of building envelope, shows that temperature gradient of 3.0-5.3°C between interior and the exterior of the building envelope was achieved. The current supplied to the TEMs are constant while the air flow rate is varied to investigate the factor on the performance of the thermoelectric. Using the TE-AD simulation model, it can be implemented to various CFD models of heat sources to predict the system performance for optimization

Preparation and caracterization of thermoelectric materials

This work presents a complete study of thermoelectric materials. It starts with a study of a Solar Concentrator and the development of a Genetic Algorithm and Cross-Entropy for analyzing experimental data. Contains a study on thermoelectric devices, from a new experimental setup. It also counts on the development and manufacture of an entire equipment for measuring thermoelectric materials, both bulks and thin films. It ends with the preparation of a specific thermoelectric material, the MoS2, and the use of all the apparatus previously developed for its study

Experimental validation and development of an advanced computational model of a transcritical carbon dioxide vapour compression cycle with a thermoelectric subcooling system

The inclusion of a thermoelectric subcooler as an alternative to increment the performance of a vapour compression cycle has been proved promising when properly designed and operated for low-medium power units. In this work, a computational model that simulates the behaviour of a carbon dioxide transcritical vapour compression cycle in conjunction with a thermoelectric subcooler system is presented. The computational tool is coded in Matlab and uses Refprop V9.1 to calculate the properties of the refrigerant at each point of the refrigeration cycle. Working conditions, effect of the heat exchangers of the subcooling system, temperature dependent thermoelectric properties, thermal contact resistances and the four thermoelectric effects are taken into account to increment its accuracy. The model has been validated using experimental data to prove the reliability and accuracy of the results obtained and shows deviations between the ±7% for the most relevant outputs. Using the validated computational tool a 13.6 % COP improvement is predicted when optimizing the total number of thermoelectric modules of the subcooling system. The computational experimentally validated tool is properly fit to aid in the design and operation of thermoelectric subcooling systems, being able to predict the optimal configuration and operation settings for the whole refrigeration plant.The authors would like to acknowledge the support of the Spanish Ministry of Science, Innovation and Universities , and European Regional Development Fund , for the funding under the RTI2018-093501-B-C21 and RTI2018-093501-B-C22 research projects. We would also like to acknowledge the support from the Education Department of the Government of Navarra, Spain with the Predoctoral Grants for Phd programs of Interest to Navarra and the Official School of Industrial Engineers of Navarre with the scholarship, Spain Fuentes Dutor

Optimization of pulsed thermoelectric materials using simulated annealing and non-linear finite elements

[EN] The objective of this work is to determine the optimal shape, gains and duration of an electric pulse applied to a Peltier cell, together with the length of the thermoelectric to maximize cooling while min- imizing electric consumption. For this purpose, a fully coupled, multiphysics, dynamic finite-element model, which solves for the thermal, electric and mechanical fields is used. Because of the demanding computing requirements of the optimization process, a special mesh is designed and a convergence anal- ysis is carried out before using the multiphysics model. The highly non-linear optimization is done by simulated annealing, a heuristic algorithm in the Markov chain Monte-Carlo family. A preliminary para- metric investigation is presented, analyzing the impact of some of the parameters. The results of this pre- liminary analysis help to understand the effect of the different shapes in the evolution of the cold face temperature. Some of these results are expected and have already been discussed elsewhere, but others can only be explained after further analysis and a full system modeling. Pulse optimization is multiobjec- tive and multiparametric, i.e., it can consider several targets such as maximizing the cooling temperature, the cooling duration or others. The trade-offs between the different targets are studied. In all cases, stres- ses inside the thermoelement are examined at all points, and the pulses must meet the restriction that an equivalent stress is not above the allowable value.This research was partially supported by the grants, Haut-de-France Region (CR Picardie, 120-2015-RDISTRUCT-000010), EU funding (FEDER, RDISTRUCT-000010) for Chaire-de-Mecanique, and Spanish Ministry of Economy and Competitiveness grant CGL2014-59841-P. These supports are gratefully acknowledgedMoreno-Navarro, P.; Pérez-Aparicio, JL.; Gómez-Hernández, JJ. (2017). Optimization of pulsed thermoelectric materials using simulated annealing and non-linear finite elements. Applied Thermal Engineering. 120:603-613. https://doi.org/10.1016/j.applthermaleng.2017.04.036S60361312

DESIGN OF A NOVEL THERMO-ELECTRIC COOLING DEVICE CAPABLE OF ACHIEVING CRYOGENIC TEMPERATURES FOR DENTAL PULP TESTING

Dental pulp testing is a diagnostic test in endodontics to test whether the dental pulp is dead or alive. Thermal tests (cold and hot) and electrical pulp testing techniques are two of the most common pulp sensibility tests currently being used. Although cold tests have shown more promising results in comparison to other techniques, the current methods used for cold testing have safety concerns as they involve direct application of the cold agent to the tooth. This study proposed a thermoelectric cooling based dental pulp testing device capable of achieving cryogenic temperatures and varying this temperature below 0℃ up to -60℃. This device is safe in operation and provides availability for on-site application due to its portability and stand-alone features. Thermoelectric cooling is based on the Peltier effect, which allows a temperature difference across a thermoelectric module and results in one side of the module becoming cold while the other side becomes hot. The challenge for such devices based on the Peltier effect is that the heat on the hot side of the module needs to be dissipated so that it is not too hot to burn the patient’s skin. This study explored the application of the phase change cooling technique in the form of heat pipes and vapor chambers to address this challenge. Finally, a thermoelectric cooling system capable of achieving -60℃ at the probe for pulp sensibility testing was proposed through modeling and simulation in Comsol Multiphysics software and experimentally validated using off-the-shelf hardware

Comparison between five stochastic global search algorithms for optimizing thermoelectric generator designs

In this study, the best settings of five heuristics are determined for solving a mixed-integer non-linear multi-objective optimization problem. The algorithms treated in the article are: ant colony optimization, genetic algorithm, particle swarm optimization, differential evolution, and teaching-learning basic algorithm. The optimization problem consists in optimizing the design of a thermoelectric device, based on a model available in literature. Results showed that the inner settings can have different effects on the algorithm performance criteria depending on the algorithm. A formulation based on the weighted sum method is introduced for solving the multiobjective optimization problem with optimal settings. It was found that the five heuristic algorithms have comparable performances. Differential evolution generated the highest number of non-dominated solutions in comparison with the other algorithms

Advancements in thermoelectric generators for enhanced hybrid photovoltaic system performance

Effective thermal management of photovoltaic cells is essential for improving its conversion efficiency and increasing its life span. Solar cell temperature and efficiency have an inverse relationship therefore, cooling of solar cells is a critical research objective which numerous researchers have paid attention to. Among the widely adopted thermal management techniques is the use of thermoelectric generators to enhance the performance of photovoltaics. Photovoltaic cells can convert the ultra-violent and visible regions of the solar spectrum into electrical energy directly while thermoelectric modules utilize the infrared region to generate electrical energy. Consequently, the combination of photovoltaic and thermoelectric generators would enable the utilization of a wider solar spectrum. In addition, the combination of both systems has the potential to provide enhanced performance due to the compensating effects of both systems. The waste heat produced from the photovoltaic can be used by the thermoelectric generator to produce additional energy thereby increasing the overall power output and efficiency of the hybrid system. However, the integration of both systems is complex because of their opposing characteristics thus, effective coupling of both systems is essential. This review presents the concepts of photovoltaics and thermoelectric energy conversion, research focus areas in the hybrid systems, applications of such systems, discussion of the most recent research accomplishments and recommendations for future research. All the essential elements and research areas in hybrid photovoltaic/thermoelectric generator are discussed in detailed therefore, this review would serve as a valuable reference literature