Reconsider Prob. 22€“87. Using an appropriate software, investigate the effects of the inlet temperature of hot water and the heat transfer coefficient on the rate of heat transfer and the surface area. Let the inlet temperature vary from 60°C to 120°C and the overall heat transfer coefficient from 750 W/m²·K to 1250 W/m²·K. Plot the rate of heat transfer and surface area as functions of the inlet temperature and the heat transfer coefficient and discuss the results.

Reconsider Prob.

Cold water (c_p = 4180 J/kg·K) leading to a shower enters a thin-walled double-pipe counter-flow heat exchanger at 15°C at a rate of 0.25 kg/s and is heated to 45°C by hot water (c_p = 4190 J/kg·K) that enters at 100°C at a rate of 3 kg/s. If the overall heat transfer coefficient is 950 W/m²·K, determine the rate of heat transfer and the heat transfer surface area of the heat exchanger using the ε-NTU method.

Transcribed Image Text:

Cold water 15°C 0.25 kg/s Hot water 100°C 3 kg/s T45°C