Cold Water 8°C Hot Gas 320 kg/h 500°C |100°C -D = 88 mm 1500 kg/h Figure 6: Counter-flow recuperator used in HVAC

Project 5:

Automobile radiator, condenser, evaporator, air preheater, and cooling tower are common types of direct heat exchangers that also called recuperators. Recuperators may have different types based on the flow arrangement of the hot and cold fluid. Your role in a company that manufactures recuperators heat exchanger is to design a counter-flow recuperator (see Figure.6) that is used in heating, ventilation, and air conditioning (HVAC).

Section.1:

− Exhaust pipe is 88 ?? diameter.

− Exhaust gas enters at 500??.

− Water jacket is used and enters at 8??.

− The surface heat coefficient of water and gas are ℎ????? = 300 ?/(?2.?) and ℎ??? = 1500 ?/(?2.?) , respectively.

− Assume conduction transfer through wall is negligible.

− The gas heat specific capacity is ?? is 1130 ?/(??.?).

− The water heat specific capacity is ?? is 4190 ?/(??.?).

− The flow rate of gas and water are 320 and 1500 ??/h, respectively.

− The gas must be cooled to 100??.

You need to design a counter-flow recuperator by calculating the required length of pipe.