Explain briefly the working of a Plate type heat exchanger. [6] ) The cold water flowing at a rate of 1.25kg/s is heated from 25C to 85C in a counter flow double-pipe heat exchanger. The pipe is made up of stainless steel with thermal conductivity of 45W/mK. The inner tube has inner diameter 1.2cm and outer diameter 1.8cm. The convection heat transfer coefficient on the inner surface of the tube is 850W/m2K and 1250W/m2K on the outer surface. The heating is accomplished by the hot water available from the power plant at 165C at a mass flow rate of 2.2kg/s. Estimate the following, (i) Overall heat transfer coefficient; [7] (ii) Log Mean Temperature Difference (LMTD); [6] (iii) Length of heat exchanger required to achieve the required heating using the outer diameter of the inner tube. 2dL [6] Take Cp of water as 4.187kJ/kgK