The heat transfer processes in the heat exchange unit of combined photoenergy system

• Дата: 2017
• Автори та афіліації: R. Zaitsev — National Technical University of Ukraine "Igor Sykorsky Kyiv Polytechnic Institute"
• Ключові слова: keywords
• Автор: Zaitsev, R.
• Формат: Стаття
• Мова: Українська
• Опубліковано: Institute of Renewable Energy National Academy of Sciences of Ukraine 2017
• Теми: heat exchanger unit; coolant; solar panels; combined photoenergy system
• Онлайн доступ: https://ve.org.ua/index.php/journal/article/view/59
• Назва журналу: Vidnovluvana energetika

Previously developed photoenergetic system based on siliconmultijunction solar cells with vertical diode cells or gallium arsenidesolar cells, which has a positioning and control facility,which increases the amount of light energy that comes to thesurface of photoenergetic system has many advantages. Suchphotoenergetic system will produce electricity and heat water, aswell. But significant weaknesses connected with a uniform coolingof installed solar cells were detected and need a separate solution.Based on aforesaid, the aim of this work was to make mathematicalmodelling of the main parameters of heat transfer blockfor such photoenergetic system based on heat transfer generalpatterns for forced fluid circulation case.Using theoretical study it was considered two options of construction:construction with a large area of the heat exchanger,and construction that has a large coefficient of heat transfer inheat exchanger area that is close to heat receiving surface. Basedon carried calculations the basic construction of a flat heat exchangerhas been improved by the insertion of microchannels forincreasing heat transfer coefficient. Heat exchanger block isdesigned as a finished unit with implementation turbulent flow init, which allows obtaining heat transfer coefficient of18 kW/(m2×k).Analysis of the received heat pictures allows concluding that atthe flowing liquid speed 0.3 m/s for the proposed construction ofthe heat exchanger sufficient uniformity of cooling surface isachieved. In this case, the maximum temperature does not exceed43.5oC, which is sufficient for effective solar cell work withoutreducing efficiency. Along with this, flowing liquid speed reducingleads to loss of cooling uniformity and to significantly increasingof the surface temperature more than 60oC, which isunacceptable.Flow analysis confirmed the turbulent regime of the flow, whichgives the maximum possible heat transfer coefficient.