A helical coil cooler is used to cool 0.5 kg.s¹ of hot oil from 100°C down to 40°C. Cooling water with an inlet temperature of 10°C flows inside the coiled tube. The specific heat of the oil is 2 kJ.kg ¹.K¹, the specific heat of the water is 4.2 kJ.kg¹.K¹, and the density of water is 1000 kg.m a) Determine the lowest possible cooling water flow rate. (0.48 kg.s¹) b) Determine the inside diameter of the tube if a cooling water flow of 1.5 times the minimum is used, and the recommended flow velocity is 1 m.s. Select an appropriate tube from the following standard sizes: Outside diameter (mm) Wall thickness (mm) 30 1.5 35 2.0 40 2.0 45 2.5 50 3.0 c) For a heat transfer coefficient of U = 800 W.m2.K, determine the heat transfer surface area and the tube length of the heat exchanger. The oil inside the tank is mixed by a stirrer and the oil temperature at any location in the tank can be assumed to be equal to the oil outlet temperature. (Area = 4.12 m², length = 39.7 m)

A rubber insulated copper wire 2 mm diameter is carrying electric current and exposed to a uniform temperature of air at 40°C. What will be the maximum steady current in amperes that can be allowed if the rubber insulation is not to get heated above 45°C? Insulation thickness=1 mm Thermal conductivity of rubber= 0.15 W/m-K Air film coefficient= 10 W/m2-K Electrical resistivity of copper=10-7 ohm-m A 10.45 A В 2.1 A C) 14.5 A D 4.25 A E 9.65 A F None of these

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5. A laboratory water bath has an immersed horizontal (cylindrical) water element, 2.54 cm. in diameter and 35cm in length, with a power input of 500 W. If the bulk water temperature is 40 °C and heat transfer occurs by free convection only, calculate the surface temperature of the heater.

Hollow Sphere Saturated steam at 267°F is flowing inside a hollow sphere with an ID of 0.824 in. and an OD of 1.05 in. The pipe is insulated with 1.5 in. of insulation on the outside. The convective heat transfer coefficient inside and outside the pipe is hi = 1000 Btu/hr/ft2/°F and ho = 2 Btu/hr/ft2/°F, respectively. The mean thermal conductivity of the metal is 45 W/m/K or 26 Btu/hr/ft/°F, while that of the insulation material is 0.064 W/m/K or 0.037 Btu/hr/ft/°F. a. Calculate the heat loss for 1 ft of pipe using resistances if the surrounding air is at 80°F. b. Calculate the temperature profile developed for this system. c. Calculate the inside and outside overall heat transfer coefficients.

Problem 3 A novel material is suddenly exposed on one side to a fluid material. The material has an overall thermal gradient of °C W -7,000 with a thermal conductivity of 23.8. The fluid m m.K • has a temperature of 30° C and a heat transfer coefficient of 325 W m². K. material. . Calculate the temperature at the surface of the

À wall of area 30 m² having a density of 1500 kg/m', thermal conductivity 30 W/m.K, and specific heat capacity 4 kJ/kg.K. The temperature distribution across a wall 0.5 m thick at a certain instant of time is given as T(x) = 30-5 x-7x The wall is generating a uniform heat (q.) of 1000 W. (1) Find the rate of heat transfer entering and leaving the wall (in W). (2) Find rate of energy stored in Watt. (3) Find (dFT/dx²) (4) Derive the change in temperature with respect to time equation (time rate of temperature change)- remember to substitute the value of (d T/dx²) from (part 3) and values of all other properties into final equation. %3D

Steel pipe (outer diameter 100 mm) is covered with two layers of insulation. The inner layer, 40 mm thick, has a thermal conductivity of 0.07 W / (m K). The outer layer, 20 mm thick, has a thermal conductivity of 0.15 W / (m K). Pipes are used to deliver steam with a pressure of 700 kPa. The temperature on the outer insulation surface is 24 ° C. If the pipe is 10 m long, determine the following: (assuming that the conduction heat transfer resistance of the steel pipe and the vapor convection resistance are negligible). a. Heat loss per hour. = AnswerkJ / hour. b. Temperature between insulation layers. = Answer° C.

need the correct ans

Please answer A