Cold Side Of Thermoelectric Module Research Articles

A new approach for simultaneous thermal management of hot and cold sides of thermoelectric modules

Thermoelectric generator systems are often exposed to unstable heat loads with high-amplitude temperature variations and there is a risk for overheating and system damage. One technique for stabilizing temperature fluctuations on thermoelectric module surfaces is utilization of phase change material. Nevertheless, the energy storage/release rate is slow due to its low thermal conductivity. This research deals with employing a foam-imbedded-phase change material on either side of the module to intensify the thermal conductivity and accelerate the heat dissipation. The thermal management strategy of the module was performed by embedding an energy storage unit on the hot side and zero-cooling energy system on the cold side. A system with external resistance over the module, integrated with phase change material containing copper foams on both sides, subjected to some heat loads, was investigated and compared with two other systems containing and lacking phase change material. A faster thermal diffusion occurred in hybrid arrangement of phase change material and foam, namely case 3, suggested a suitable alternative over the case containing only phase change material (case 2). Adding the foam enhances the heat flux through the phase change material by reducing the overall thermal resistance in the energy storage unit. Replacing the case 2 with new case 3 diminished the hot and cold side temperatures without decreasing the output voltage up to 8% and 7%, respectively. Case 3 produced energy for a longer time comparing case 2 before reaching the critical conditions. This study offers a practical solution for design of autonomous and self-sufficient systems with zero-cooling energy and higher safety under dynamic thermal sources.

Performance study of thermoelectric dehumidification system integrated with heat pipe heatsink

The thermoelectric (TE) cooler is a key component in a TE dehumidifier system. This study represents an experimental investigation on the performance of the TE dehumidifier system integrated with heat pipe heatsink. The system is composed of TE modules, fin heatsink, and heat pipe heatsinks. A rectangular fin heatsink is attached to the cold side of TE modules, while the heat pipe heatsink are mounted to the hot side. Air circulates from the test chamber through the cold-side heatsink to remove moisture, and heat pipe heatsink are used to dissipate heat from the hot side of the TE modules. The effect of relevant parameters such as electrical current input to the TE modules and cold air flow rate on the system's performance is studied. It is found that the cold air flow rate and the electrical current input to the TE modules have the highest impact on the system's performance. Improvements to the coefficient of performance (COP) and cooling capacity of the system can be achieved by using heat pipe heatsinks. Experimental results show that the optimum occurs at 3 A of electrical current input to the TE modules and 1.34 g/s of cold air flow rate with corresponding cooling capacity of 93.1 W, yielding an effectiveness of 2.638E-07 L/J and a coefficient of performance (COP) of 1.1.

Performance Improvement of Thermoelectric Air Cooler System by Using Variable-Pulse Current for Building Applications

The thermoelectric air conditioning system (TE-AC) is a small, noiseless alternative to standard vapor compression refrigeration (VCR) systems. The cooling characteristics of a TE-AC system operating under two conditions, i.e., steady current and current pulses, are investigated in this study. This system consists of three thermoelectric modules, a heat sink, and an air circulation fan. The result shows that maximum temperature reduction in cooling side of TE-AC system was achieved at 6 A input current under steady state operation. The optimum performance of the TE-AC system under steady state operation depends upon the combined effect of the cooling load, Joule, Fourier, and Peltier heat. In TE-AC pulse operation, both current width and cooling load applied on the cold side of the thermoelectric module (TEMs) play an important role in achieving optimum cooling performance of the system. When normal input current operation (i.e., no current pulse) was compared to pulse-operated TE-AC system operation, it was found that pulse operation provides an additional average temperature reduction of 3–4 °C on the cold side of TEMs. Although on the hot side, it maintains a temperature in the range of 18 °C to 24 °C to reduce overshoot heat flux. The duration of operation is also important in determining pulse width and pulse amplitude. Minimum and overshoot peak temperature rises during each cycle for longer run operation. In the TE-AC system, the accumulated Joule heat during a current pulse frequently causes a temperature overshoot, which lasts much longer. As a result, the next current pulse was not released until the temperature of TE was restored to its initial value.

The performance of thermoelectric exhaust heat recovery system considering different heat source’s fin arrangements

The IC engine converts the chemical energy of the fuels into the mechanic energy with the efficiency is around 35-40% depends on the type and operation condition of the engines. It means around 60-65% of the energy is wasted mostly in the form of heat (dissipated through the cooling process and exhaust gas) and friction. A thermoelectric exhaust heat recovery system can be used to harvest the waste heat which potentially could increase the efficiency of the IC engine indirectly. In this experimental study, the heat recovery system consists of a rectangular duct in which sixteen thermoelectric modules are attached to its sides (each side consist of four thermoelectric modules). The aluminium fins are mounted at the cold sides of thermoelectric modules (at the outer sides of the rectangular duct) and cooled by air supplied by computer fan coolers. To harvest the exhaust heat of the IC engine, the heat recovery system is connected to the exhaust pipe. The effect of aluminium fin arrangements, mounted on the inner surfaces of the rectangular duct of the heat recovery device, is investigated. The arrangements include mounting of the fins at the lateral sides, top and down sides, and the whole sides of the heat recovery device. Besides, the effect of the absence of the fins at the exhaust gas passage of the heat recovery device is examined. The performance of the heat recovery system is studied when the engine operates under the no-load condition at rotational speeds of 1300, 1600, 1900 and 2200 RPM. The experimental result reveals that the voltage and current generated by the thermoelectric exhaust gas recovery system increase in line with the increase of engine speed. In addition, it is found that the highest voltage and current are generated by the whole side fin arrangement, namely 12,52V and 122 mA respectively, at an engine speed of 2200 RPM. It is observed that the finless arrangement generates the lowest voltage and current among others, namely 5.36 V and 20.43 mA.

Sensitivity analysis of the effects of the thermal parameters of exhaust gases on the output of a thermoelectric generator

AbstractRecovering the dissipated heat from exhaust is a useful means of reducing the energy consumption level as well as cutting down on environmental pollution. An efficient technique for recovering this lost heat is the use of thermoelectric generators, which directly convert the dissipated heat into useful electrical energy. In this paper, a whole thermoelectric generator system installed on the exhaust pipe of a vehicle has been modeled, and the effects of thermal parameters on the output of this thermoelectric generator have been measured and evaluated by means of sensitivity analysis. The E‐Fast sensitivity analysis method has been used in this study. The sensitivity analysis results indicate that, among the thermal parameters examined, the temperature of gases entering the heat sink installed at exhaust pipe outlet () has the greatest influence (37%) and the flow rate of fluid entering the heatsink installed on the cold side of thermoelectric modules () has the second greatest influence (17%) on the output power of the considered thermoelectric generator. By using these results, the best cases of hot exhaust gases from various industries and vehicles with the highest potential of recovering the dissipated energy and heat from them by thermoelectric generators can be identified.

Effective design, theoretical and experimental assessment of a solar thermoelectric cooling-heating system

This study performed a theoretical and experimental assessment of a solar thermoelectric cooling-heating system using photovoltaic (PV) collector in the weather conditions of Sanandaj, Iran. The thermoelectric cooling system was tested as an auxiliary system from 11:00 to 12:12 to reduce the power consumption of compression cooling system and to increase its coefficient of performance from 12:00 to 18:00. The results were reported for a thermoelectric system tested during the given period. The maximum voltage and current applied to the thermoelectric system were 12 V and 3.043 A, respectively. The coefficient of performance in this maximum input power was calculated to be 1. Total energy consumption of thermoelectric system and energy generation of PV collector from 11:00 to 12:12 were found to be 56.465 and 361.406 kJ, respectively. The minimum temperature of cooling chamber and maximum outlet water temperature of thermoelectric system at maximum input power consumption were 12 and 45 °C, respectively, and temperature of the hot and cold sides of thermoelectric module in this consumption power were 69 and −3 °C, respectively, which were found to be noticeable. The findings showed that the operation time, energy consumption and coefficient of performance of compression cooling system and thermoelectric hybrid cooling system were 16,380 s, 8636.8 kJ and 5.3 and 15,000 s, 7911 kJ and 5.4, respectively, indicating a better performance for the hybrid cooling system.

Effective use of thermal energy at both hot and cold side of thermoelectric module for developing efficient thermoelectric water distillation system

An efficient thermoelectric distillation system has been designed and constructed for production of drinkable water. The unique design of this system is to use the heat from hot side of the thermoelectric module for water evaporation and the cold side for vapour condensation simultaneously. This novel design significantly reduces energy consumption and improves the system performance. The results of experiments show that the average water production is 28.5mL/h with a specific energy consumption of 0.00114kWh/mL in an evaporation chamber filled with 10×10×30mm3 of water. This is significantly lower than the energy consumption required by other existing thermoelectric distillation systems. The results also show that a maximum temperature difference between the hot and cold side of the thermoelectric module is 42.3°C, which led to temperature increases of 26.4°C and 8.4°C in water and vapour, respectively.

Assessing the accuracy of mathematical models used in thermoelectric simulation: Thermal influence of insulated air zone and radiation heat

An accurate mathematical model of thermoelectric modules (TEMs) provides the basis for the analysis and design of thermoelectric conversion system. TEM models from the literature are only valid for the heat transfer of N-type and P-type thermoelectric couples without considering air around the actual thermoelectric couples of TEMs. In fact, air space imposes significant influence on the model computational accuracy, especially for a TEM with large air space inside. In this study, heat transfer analyses of air between the TEM cold and hot plates were carried out in order to propose a new mathematical model that minimises simulation errors. This model was applied to analyse characteristic parameters of two typical TEMs, and the ratio of cross-sectional area of air space to thermocouples were 48.2% and 80.0%, respectively. The average relative errors in simulation decreased from 5.2% to 2.8% and from 12.8% to 3.7%, respectively. It is noted that our new model gives result more accurate than models from the literature provided that higher temperature difference occurs between hot side and cold side of TEM. Thus, the proposed model is of theoretical significance in guiding future design of TEMs for high-power or large-temperature-difference thermoelectric conversion systems.

Electricity Generation from a Solar Parabolic Concentrator Coupled to a Thermoelectric Module

The concept of generating electricity from the sun's energy using a parabolic concentrator and a thermoelectric (TE) module is presented in this study. The proposed TE solar concentrator was composed of a parabolic dish collector with an aperture of 1.5 m that was used to concentrate sunlight onto a receiver plate with an area of 10 × 10 cm2. One BiTe-based TE module installed on the receiver plate was used to convert the concentrated solar thermal energy directly into electric energy. A rectangular fin heat sink coupled with a fan was used to release heat from the cold side of TE module and a tracking system was used to continuously track the sun. The effects of fan orientation and air flow rate were investigated. Under maximum heat flux, the TE module was able to produce 1.32W at 0.42 m3/min of the air flow rate (pushing air), corresponding to 2.89% conversion efficiency. The proposed concept seems to be reliable and merits further investigation.

Research on the Compatibility of the Cooling Unit in an Automotive Exhaust-based Thermoelectric Generator and Engine Cooling System

The temperature difference between the hot and cold sides of thermoelectric modules is a key factor affecting the conversion efficiency of an automotive exhaust-based thermoelectric generator (TEG). In the work discussed in this paper the compatibility of TEG cooling unit and engine cooling system was studied on the basis of the heat transfer characteristics of the TEG. A new engine-cooling system in which a TEG cooling unit was inserted was simulated at high power and high vehicle speed, and at high power and low vehicle speed, to obtain temperatures and flow rates of critical inlets and outlets. The results show that coolant temperature exceeds its boiling point at high power and low vehicle speed, so the new system cannot meet cooling requirements under these conditions. Measures for improvement to optimize the cooling system are proposed, and provide a basis for future research.