DESIGN AND PERFORMANCE OF THE ACTIVE SOLAR COLLECTOR

D. Ristoiu1, C. Cosma1, T. Ristoiu2, O. Cozar3, D. Cenan2

1University Babes-Bolyai, Faculty of Environmental Science, Str. M. Kogalniceanu nr.4, 400084, tel. +4 0264 405316, Cluj-Napoca, Romania, 
2Technical University, Cluj-Napoca, Str. Constantin Daicoviciu nr 15, 400020 Cluj- Napoca, Romania tel. +4 0264 401 200,  Romania
3University Babes-Bolyai, Faculty of Physics, Str. M. Kogalniceanu nr.1, 400084, tel. +4 0264 405300, Cluj-Napoca, Romania, 

	An active solar collector is a device that utilises the solar radiation to heat a fluid (usually water), which can then be used for suitable applications.  This is done by absorbing the solar radiation on an absorber plate and thus heating it.  This heat is then transferred to a circulating fluid for use elsewhere.
	Knowing the mechanisms of heat transfer involved in the flat plate solar collector, we can now estimate the losses occuring in the collector system.  This will help in identifying areas where particular losses (for example, radiation) are high and thus change/modify configurations to reduce them.  In this context, it is important to note that the losses occur from the region of high temperature to the region of low temperature (i.e. from the absorber plate to the ambient).
	In this paper the heat losses from the various components of the active solar collector will be first studied so as to obtain the overall heat loss coefficient factor, which can depict the losses for the entire collector.