Performance enhancement of mini thermoelectric refrigerator by using thermoelectric module cooled with paraffin phase change material (PCM) heat sink

Mansor, Muhammad Hazim (2023) Performance enhancement of mini thermoelectric refrigerator by using thermoelectric module cooled with paraffin phase change material (PCM) heat sink. Project Report. Melaka, Malaysia, Universiti Teknikal Malaysia Melaka. (Submitted)

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Abstract

The release of refrigerants particularly chlorofluorocarbons (CFC) and hydrofluorocarbons (HCFC) by human activities from vapor compression refrigeration systems has had a negative influence on the environment. This problem necessitates the development of more environmentally friendly and energy-efficient air-conditioning and refrigeration technologies. One of the most promising solutions to meet this need is by developing efficient thermoelectric refrigerators. Thermoelectric modules were used as the major components in this study to create a mini thermoelectric refrigerator. When electric current is supplied to a thermoelectric module, one side of the thermoelectric module becomes hot and the other side is cold. The cold side can be utilized for cooling purposes. However, the hot side of the module tends to become so hot that it requires a heat sink to efficiently dissipate the heat to the surrounding environment. The study aims to evaluate the best design of heat sink with phase change material (PCM) to reduce the hot side temperature of the module to achieve a lower cooling temperature and increase the coefficient of performance (COP) of the mini thermoelectric refrigerator. Paraffin PCM is an organic PCM that used in this study has melty temperature of 59.1 ˚C and heat of fussion (ΔH) of 127.3 kJ/kg. This thermal energy storage materials melts when the heat sink temperature of the hot side of the thermoelectric module exceeds its melty temperature. The thermoelectric module was also impacted by the type of heat sink selected. To ascertain which form of heat sink can enhance the heat rejection of a hot-side thermoelectric module, this study uses two different types of heat sinks: a copper plate heat sink and a fin heat sink. The fin heat sink can reduce the cold temperature of the thermoelectric unit better. Hence, it was chosen for this study. The data for this study and research was gathered in 1 minute interval for 10 minutes. The temperature of the cold side and hot side when copper plate PCM heat sink was used were 39.2 ˚C and 108.8 ˚C respectively. However, when fin PCM heat sink was used, the temperature of cold and hot side of thermoelectric module were 6.4 ˚C and 29.9 ˚C respectively. It become that fin PCM heat sink is a better cooling medium. The PCM was macro encapsulated in aluminium foil and the attached to the fin heat sink on the hot side of the thermoelectric module to increased the heat rejection. Therefore, a mini thermoelectric refrigerator with fin PCM heat sink was employe for future investigation superior heat rejection capability. The effectiveness of PCM as a cooling medium has was proved with experiment evidence that without PCM, the hot side temperature of the module is 29. 0 ˚C where with PCM the temperature was 27.6 ˚C. The thermoelectric refrigerator cooling space temperature also can reduce with increasing mass of PCM. When 3 gram of PCM were applied, the cooling space drops to 11.9 ˚C and achieve lower 11.0 ˚C when 6 gram of PCM was utilized. Depending on the mass of PCM, various cooling space temperature can be achieved. The coefficient of performance for a thermoelectric unit using copper plate heat is 18.22 %. On top of that, the coefficient of performance of a thermoelectric unit using a fin heat sink is 7.49 %. The use of PCM raises the thermoelectric unit's coefficient of performance to 8.34 %. Based on the results, it is possible to draw a conclusion that PCM heat sink is an efficient cooling medium of the hot side of thermoelectric module. Thus enable the mini thermoelectric refrigerator to achieve lower cooling space temperature.

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