A thermal energy storage unit consists of a large rectangular channel, which is well insulated on its outer surface and encloses alternating layers of the storage material and the flow passage.
Each layer of the storage material is an aluminum slab of width
Want to see the full answer?
Check out a sample textbook solutionChapter 3 Solutions
Introduction to Heat Transfer
- 7.43 Liquid sodium is to be heated from 500 K to 600 K by passing it at a flow rate of 5.0 kg/s through a 5-cmID tube whose surface is maintained at 620 K. What length of tube is required?arrow_forward2.42 A circumferential fin of rectangular cross section, 3.7-cm OD and 0.3 cm thick, surrounds a 2.5-cm- diameter tube as shown below. The fin is constructed of mild steel. Air blowing over the fin produces a heat transfer coefficient of K. If the temperatures of the base of the fin and the air are and , respectively, calculate the heat transfer rate from the fin.arrow_forwardThe air-conditioning system in a Chevrolet van for use in desert climates is to be sized. The system is to maintain an interior temperature of 20C when the van travels at 100 km/h through dry air at 30C at night. If the top of the van is idealized as a flat plate 6 m long and 2 m wide and the sides as flat plates 3 m tall and 6 m long, estimate the rate at which heat must be removed from the interior to maintain the specifiedarrow_forward
- The heat transfer coefficient for a gas flowing over a thin float plate 3-m long and 0.3-m wide varies with distance from the leading edge according to hc(x)=10x1/4Wm2K If the plate temperature is 170C and the gas temperature is 30C, calculate (a) the average heat transfer coefficient, (b) the rate of heat transfer between the plate and the gas, and (c) the local heat flux 2 m from the leading edge. Problem 1.18arrow_forward3.14 A thin-wall cylindrical vessel (1 m in diameter) is filled to a depth of 1.2 m with water at an initial temperature of 15°C. The water is well stirred by a mechanical agitator. Estimate the time required to heat the water to 50°C if the tank is suddenly immersed in oil at 105°C. The overall heat transfer coefficient between the oil and the water is , and the effective heat transfer surface is .arrow_forward2.7 A very thin silicon chip is bonded to a 6-mm thick aluminum substrate by a 0.02-mm thick epoxy glue. Both surfaces of this chip-aluminum system are cooled by air at , where the convective heat transfer coefficient of air flow is . If the heat dissipation per unit area from the chip is under steady-state conditions, draw the thermal circuit for the system and determine the operating temperature of the chip.arrow_forward
- Determine the rate of heat transfer per meter length to a light oil flowing through a 2.5-cm-ID, 60-cm-long copper tube at a velocity of 0.03 m/s. The oil enters the tube at 16C, and the tube is heated by steam condensing on its outer surface at atmospheric pressure with a heat transfer coefficient of 11.3 kW/m K. The properties of the oil at various temperatures are listed in the following table: Temperature, T(C) 15 30 40 65 100 (kg/m3) 912 912 896 880 864 c(kJ/kgK) 1.80 1.84 1.925 2.0 2.135 k(W/mK) 0.133 0.133 0.131 0.129 0.128 (kg/ms) 0.089 0.0414 0.023 0.00786 0.0033 Pr 1204 573 338 122 55arrow_forwardA Pressurized Water Reactor fuel rod is 12 ft long and 0.374 inches in diameter (outer) on a 0.496 inch square pitch. The fuel pellet diameter is 0.3225 inches. The fuel rod gap is constant with a width of 0.0065 inches. The system pressure is 2250 psia and can be assumed to be constant. The rod operates at linear heat rate of 12.1 kW/ft. At the elevation of interest, the coolant temperature is 575 °F with a convective heat transfer coefficient of 6200- For this elevation determine the temperature BTU hr ft²F margin to boiling according to Jens-Lottes. Also assume constant fluid properties given as: p=46.39 Ibm = ,c. 1.261- BTU Ibm-F BTU -,k=0.334- hr-ft-F Ibm ft-hr M=0.222- -, Tsat 652.7F =arrow_forwardHeat transferarrow_forward
- Water at 340 K and a flow rate of 5 kg/s enters a black, thin-walled tube, which passes through a large furnace whose walls and air are at a temperature of 700 K. The diameter and length of the tube are 0.25 m and 8 m, respectively. Convection coefficients associated with water flow through the tube and airflow over the tube are 300 W/m²-K and 50 W/m².K, respectively. Water Tme= i m = 5 kg/s Tai K Tube, D = 0.25 m L = 8 m, ε = 1 Air T= 700 K -Furnace, Tur 700 K Write an expression for the linearized radiation coefficient corresponding to radiation exchange between the outer surface of the pipe and the furnace walls. Determine how to calculate this coefficient if the surface temperature of the tube is represented by the arithmetic mean of its inlet and outlet values. Use these expressions to determine the outlet temperature of the water, Tm,o, in K. Tmoarrow_forwardThese are different problem from other problems postedarrow_forwardA steel tube 150mm inside diameter and 10mm thick, conveys wet steam at 17 bar and is surrounded by air at 27°C. The coefficient of heat transfer from the steam to the tube is 10kW/m2 K and the thermal conductivity for steel is 46.6 W/mK. Under these circumstances the energy loss due to heat transfer is 2000W per metre length of pipe. Show that, because the resistance to heat transfer is comparatively small between the steam and the pipe and within the pipe, the corresponding temperature drops are small compared with the temperature drop between the outside surface of the pipe and the air. If the pipe is covered with a 50mm thick layer of insulating material which has a thermal conductivity of 0.346 W/mK, determine the heat loss in watts per metre length of pipe, and the rate of condensation per 100m of pipeline under these conditions. Assume that the heat transfer coefficient from the surface of the insulating material to the air is 0.714 times that for the bare pipe. Answer: 609…arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning