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A cartridge electrical heater is shaped as a cylinder oflength
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Fundamentals of Heat and Mass Transfer
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Introduction to Heat Transfer
- In a thermal power plant, a horizontal copper pipe of "D" diameter, "L" length and thickness 1.9 cm enters into the boiler that has the thermal conductivity as 0.37 W/mK. The boiler is maintained at 102 °C and temperature of the water that flows inside the pipe is at 34°C. If the energy transfer (Q) is 100735 kJ in 7 hours. Determine the Heat transfer rate, Surface area of the pipe and Diameter & Length of the pipe, if D = 0.015 L .arrow_forwardA 10 gallons of water has an inital temperature of 25 degrees Celsius. What is the input power needed to raise the temperature up to the boiling point after 25 minutes Assume heat loss 12%arrow_forwardSolve for the latent heat of water at Tw = 28C(and. λw = 2435 kJ/kg)arrow_forward
- The surface temperature of a heater with a diameter of 50 mm in a horizontal position is 40°C. This heaterIt was immersed in water at 20°C. Find the heat lost per unit length of the heater.arrow_forwardn electric generator at a power plant produces energy by passing superheated steam from a high temperature container (reservoir), through a pipe connected to a series of fans, and then into a low temperature reservoir. As the steam passes across the blades of the fans some of the heat energy of the steam is transformed into mechanical energy, which turns the fans which in turn are connected to a generator, which in turn converts the mechanical energy into electrical energy. If the high temperature steam has a temperature of 412.1 K and the low temperature reservoir has a temperature of 105.4 K, what is the Carnot efficiency of this process?arrow_forwardThe net radiant-heat exchange between a 20-by-20 ft rough plaster panel-heated ceiling and a 20-by-10-ft side wall, which has an emissivity of 0.80, is 2400 Btu/hr. If the surface temperature of the ceiling is 120 deg. F, determine the average surface temperature of the side wall.arrow_forward
- In a thermal power plant, a vertical copper pipe of "D" diameter, "H" height and thickness 1 cm enters into the boiler that has the thermal conductivity as 0.35 W/mK. The boiler is maintained at 102C and temperature of the water that flows inside the pipe is at 25C. If the energy transfer (Q) is 119031 kJ in 7 hours. Determine the Heat transfer rate, Surface area of the pipe and Diameter & Height of the pipe, if H = 27 D.arrow_forwardWater (5.2 L/min) is flowing in a tube "D= 3 cm, L= 5 m" and is to be heated from 15°C to 59.9°C by applying a uniform heat flux on the outer surface of the tube by electric resistance heater. What is the power rating of the resistance heater (kW)? 0.8 II If turbulent flow use Dituss-Boetler relation Nu= 0.023 Re Pr. 3 Properties : p = 992.1 kg/m , C 4179 J/kg. °C, k=0.631 W/m°C, Pr= 4.32, v= 0.658E-6 m /s Select one:arrow_forwardA power station uses oil-fired boilers which are supplied with fuel from 4 cylindrical tanks, each with 12 m diameter and 11 m high. The calorific value of the oil is 38,039 kJ/kg and its relative density is 0.78. The output from the power station is 77 MW. Assuming the only 21% of the heat input is converted to into electrical energy output, how long will the boilers run (in days) on the oil in the tanks. Correct Answer: 4.7 ± 0.1arrow_forward
- (heat transfer ) thanks The velocity of the fluid flowing in parallel over a 500mmx500mm flat heater surface is U= 19 m/s and the inlet velocity temperature is T_∞15 C. The surface temperature of this plate is T_s140 C, the friction force is F_D=0.4 N and the surface area of the plate is A=0.32 m2. According to this;(F_D= 0.4N A=32 m2)a) Surface shear stressb) Find the coefficient of frictionc) Heat transfer coefficientd) What is the amount of heat transfer (electric power) that must be given to maintain a constant surface temperature?arrow_forward• An aluminum pot contains water that is kept steadily boiling (100 °C). The bottom surface of the pot, which is 12 mm thick and 1.5x10t mm2 in area, is maintained at a temperature of 102°C by an electric heating unit. Find the rate at which heat is transferred through the bottom surface. Compare this with a copper based pot. Tc 0 0 L=12mm Base of pot TH A= area of basearrow_forward5. Consider a carton of milk that is refrigerated at a temperature of Tm = 5 °C. The kitchen temperature on a hot summer day is T- -30 °C. If the four sides of the carton are of height and width L = 200 mm and w= 100 mm, respectively, determine the heat transferred to the milk carton as it sits on the kitchen counter for durations of t=10 s, 60 s, and 300 s before it is returned to the refrigerator. The convection coefficient associated with natural convection on the sides of the carton is h = 10 W/m²K. The surface emissivity is 0.90. Assume the milk carton temperature remains at 5 °C during the process. Your parents have taught you the importance of refrigerating certain foods from the food safety perspective. Comment on the importance of quickly returning the milk carton to the refrigerator from an energy conservation point of view.arrow_forward
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