OPTIMIZATION OF THE HEAT EXCHANGER IN A FLAT PLATE INDIRECT HEATING SOLAR WATER HEATING SYSTEM

Most of the modern day energy needs is being supplied by fossil fuels and these are consumed at such a rate that the reserves of oil and gas would last for not more than 250 years. If we try to see the implications of these limited reserves we will be faced with a situation in which the un it cost of energy will be high and concern about the envir onmental pollution caused by burning of the fossil fuels. Solar energy is o ne of the important rene wable energy source and an important application i n the water heating for domestic and industrial purposes . It incorporates the collection o f a so lar energy and hot water storage in one unit. The aim is to investigate the effect of different parameters on the thermal performance of this system with the aim of reducing both the initial and the running costs. The outlet service water temperature was used as a measure of performance, because it is an indicator of the energy acquired from the solar radiation. The continuity, momentum and energy equations of the fluids involved in the system were numerically solved in a steady state condition, using FLUE NT software. Three - D CFD models were developed and validated using previous experimental results. A standard k - ω turbulent model was used in the opt imization of the heat exchanger. The surface - to - surface radiation model was included. The effect of single and double row heat excha ngers with different lengths investigated. Circular and elliptic cross - section pipes were also examined. Mass flow rates of 500 and 650 L/h were cho o sen. The results showed that the single row HX of 10.8 m length for both the ellip tical and type B tube gave high s ervice water outlet temperature and with low pumping power.