Abdelrahman M. Elshaer1, A. M. A. Soliman1,2, M. Kassab3, and A. A. Hawwash1, 1Department of Mechanical engineering, Benha faculty of engineering, Benha University, Benha city, Egypt, 2Faculty of Engineering and Technology, Badr University in Cairo (BUC), Cairo, Egypt, 3Mechanical systems design department, Egyptian space agency, New Cairo, Egypt
Thermal control of electronics aims to maintain their temperature within the recommended temperature range. Satellite avionics are getting smaller and have a higher power density. Furthermore, the heat transfer modes in space are limited to conduction and radiation, which makes thermal control more difficult. Thermal energy storage materials are a promising candidate for the thermal control of satellite avionics. Solid-liquid Phase change materials (PCMs) are latent heat thermal storage materials that store and release thermal energy during melting and solidification. The best method for using the PCMs in thermal control of satellite avionics is PCM encapsulation. PCM encapsulation refers to packing the PCM into a closed rigid container to isolate it from the surrounding. In the present work, a PCM-based heat sink was adopted for thermal control of a small satellite subsystem. The heat sink was made of aluminium due to its relatively high thermal conductivity and was designed based on the outer dimensions of a small satellite subsystem. RT 35, RT 31, and RT 24 were used as the PCM materials, and thermal conductivity enhancers (TCE) with different geometries were used to get over the lower thermal conductivity of the PCM. The present study delivers a transient numerical investigation of the effect of TCE geometry on the thermal control performance of the PCM-based heat sink. Circular pin fins, triangular pin fins, and novel metal foam geometry were used with a TCE volume fraction of 20 %. The electronic subsystem was assumed to be "ON" for 10 min generating 20 W of heat, and "OFF" for 80 min. During the cycle, the heat sink's base plate temperature and the liquid fraction of PCM were recorded. The results showed a significant decrease in the base plate temperature when the PCM was used. RT 24 reduced the temperature by about 46 % compared to the case without PCM. At the lower melting points PCM recorded a higher liquid fraction. RT 24 increased the liquid fraction by 27.7 %. The results also concluded that the novel metal foam geometry significantly enhanced thermal performance and delivered the lowest base plate temperature.
Phase change materials (PCM) - PCM encapsulation - Heat sink - Thermal control – Thermal conductivity enhancer (TCE).
Kamel Adref, Mohamed Omar Bamatraf, Abdullah Saleh Aljabri, Abdulrahman Sulaiman AlAkbari, Abdulrahman Salem AlAkbar, Zayed Ahmed AlHashmi, Department of Mechanical Engineering, Higher Colleges of technology, Abu Dhabi Mens College, UAE
This paper represents the results of a capstone project that took place in the mechanical engineering department at Abu Dhabi Mens College. Emphasis was placed on determininghow much cooling can be stored in a 10 L water tank from 3 water thermoelectric coolers(WTCs) connected thermally in series. The results obtained were analyzed for 3 different scenarios, a) one WTC, b) 2 WTCs, c) 3 WTCs and two different mass flow rates of 0.02 kg/s and 0.04 kg/s. A decrease in the water storage tank temperature with time was shown under all the conditionsthe experiments were conducted. On the other hand an increase in the amount of cooling capacity in the water storage tank was observed. Of interest,the results showed that the rate with which the storage tank temperature gradient and consequently the amount of cooling stored decreased as the number of the connected WTCs was increased.
Thermoelectric Water Cooler, Cooling Capacity, Stored energy.