Mathematical Modelling of a Three Tube Heat Exchanger for Hot Two Pass and Cold one Pass Flow (Both from Front end) Arrangement

A three tube heat exchanger is a special type of H.E having three concentric tubes with multi-pass arrangements for one of the fluid. This is a mixed type of heat exchanger which is neither pure counter flow nor pure parallel flow. Simultaneously it gives both parallel and counter flow arrangements for any flow directions of two fluids. This is also a type of multi-pass and a compact type of heat exchanger. The work involved in this investigation is to analyze the performance of 3-tube heat exchanger by formulating differential equations using energy balance in differential form. These differential equations are solved by using a numerical technique viz., by 4th order Runge-Kutta method with boundary conditions. Figure numbers 5 to 8 shows the temperature plots along the length of the three tube heat exchanger in dimensionless form. The plots are obtained for four different values of F, which is a capacity rate ratio. The temperature profile nature is as expected for different arrangements resulting from entry of hot and cold fluids. By using this temperature plots effectiveness and NTU are determined for different capacity rate ratios. The results are concluded at the end.