counter-flow heat exchanger, water entering at 1 kg/s is heated from 23°C to 69°C as it flows thru the inner pipe. Hot oil enters the heat exchanger at 2 kg/s and 110°C. The convection heat transfer coefficients in the cold- and hot-sides are 100 and 50 kW/m2∙°C, respectively. Calculate the

A thin-walled double-pipe heat exchanger is to be used to cool oil (cp= 2500 J/kg-K) from 80°C to 50°C at a rate of 5 kg/s by water (cp= 4200 J/kg.K) that enters at 20°C at a rate of 2 kg/s. The diameter and length of the tube considered for the heat exchanger is 2.5 cm and 2 meters. The convective heat transfer coefficients for the oil and water are assumed to be ho = 400- and W m²c W hw = 600 , respectively. m²c' a. Determine if a parallel or counter flow heat exchanger should be used in this case (tell reason and show calculation) b. Using LMTD method, determine the number of pipes required for the heat exchanger

A fruit juice is being heated in an indirect heat exchanger using steam as a heating medium. The product fl ows through the heat exchanger at a rate of 1500 kg/h and the inlet temperature is 20C. Determine the quantity of steam required to heat the product to 100C when only latent heat of vaporization (2200 kJ/kg) is used for heating. The specifi c heat of the product is 4 kJ/(kg C).

The oil (cp = 1 795 W-s/kg-K) from an oil-cooled electric transformer is cooled from 79.4 oC to 29.4 oC at the rate of 1 360.5 kg/h. This is done in an oil-water het exchanger that receives 2 948 kg/h of water at 15.6 Celsius. For the exchanger, U = 295 W/m2-K. Find the exit water temperature and heating area required (a) for counter flow and (b) for parallel flow.

A long, thin-walled double-pipe heat exchanger with tube and shell diameters of 0.01 m and 0.025 m, respectively, is used to condense refrigerant-134a with water at 20°C. The refrigerant flows through the tube, with a convection heat transfer coefficient of hi= 4100 W/m² °C. Water flows through the shell at a rate of 0.3 kg/s. The thermal resistance of the inner tube is negligible since the tube material is highly conductive and its thickness is negligible. Both the water and refrigerant-134a flows are fully developed. Properties of the water and refrigerant-134a are constant. Water properties: p = 998 kg/m³, v=u/p-1.004x 10-6 m²/s, k = 0.598 W/m. °C, Pr = 7.01 Cold water D Do