Due to increasing the prices of fish and animal feed, a big gap in feed nutrition is generated. Also the increment necessitates of the sources of animal protein creates and maximize this nutritional gap in Egypt. So the creation of local and alternative source of feed concentrates instead of import is needed. Huge quantities of small sizes of fish are thrown on land without any manipulation during fish ponds harvesting. It is necessary to process and recycle these wastes in order to be a useful component. Drying process was used in the present investigation for fish wastes treatment that adds to obtain feed concentrates with low costs (Fishmeal). Therefore, the objective of this research work is to dry a sample of the whole fish waste, by using the heat exchangers, at the experimental station of Rice Mechanization Center (RMC), Meet Eldeebah village, Kafr Elsheikh Governorate during September of the year 2015 by using a stream of hot air at different drying air velocities of 1.5, 2 and 3m/s. The manufactured heat exchanger has the cylindrical shape. Its dimensions were of 30.48cm in diameter internal, 50cm in diameter external and 150cm long. The heat exchanger is connected with a flat plate solar collector with the dimensions of 100 x 100cm. The working medium in the heat exchanger is the hot water output of flat plate solar collector. The extreme values of thermal energy stored in water and thermal efficiency of the solar system are of 50.284 and 53.549%, respectively.
Maximum effectiveness of the parallel flow system was of 28.152% with the drying air velocity of 1.5m/s, whereas for the counter flow system was of 19.46% with the drying air velocity of 2m/s. Also, the highest values of heat energy transferred rate from water to air were of 2.21kW and 2.81kW with the drying air velocity of 3m/s for the parallel and counter flow heat exchangers, respectively. In general the counter is better than the parallel system with the maximum drying rate of 0.42kg water/(kg dry matter. min) at drying air velocity of 1.5m/s. Maximum internal energy of water tank was of 6.09kJ at 5.00PM, temperature of water was of 40.6ᵒC and less radiation was of 77.43W/m2. In addition, maximum exergy rate of the parallel flow system was of 2.49kW with drying air velocity of 2m/s, whereas for the counter flow system was of 0.433kW with the drying air velocity of 3m/s.Maximum specific enthalpy of the parallel and counter drier units of drying air are of 214.56 and 180kJ/kg at drying air velocity of 2m/s, respectively. While specific enthalpy of drying air of counter drier unit is higher than that of parallel one at drying air velocities of 1.5 and 3m/s while lower at drying air velocity of 2m/s.