An ice-skating rink is located in an indoor shopping mall with an environmental air temperature of 22-C and radiation surrounding walls of about 25-C. The convection heat-transfer coefficient between the ice and air is about 10 W/m2 - C because of air movement and the skaters' motion. The emissivity of the ice is about 0.95. Calculate the cooling required to maintain the ice at 0-C for an ice rink having dimensions of 12 by 40 m. Obtain a value for the heat of fusion of ice and estimate how long it would take e to melt 3 mm of ice from the surface of the rink if no cooling is supplied and the surface is considered insulated on the back side. 4. An ice-skating rink is located in an indoor shopping mall with an environmental airtemperature of 22•C and radiation surrounding walls of about 25•C. The convectionheat-transfer coefficient between the ice and air is about 10 W/m2 · •C because of airmovement and the skaters' motion. The emissivity of the ice is about 0.95. Calculatethe cooling required to maintain the ice at 0•C for an ice rink having dimensions of 12by 40 m. Obtain a value for the heat of fusion of ice and estimate how long it wouldtake to melt 3 mm of ice from the surface of the rink if no cooling is supplied and thesurface is considered insulated on the back side.

Given data as per question Environmental temperature =220 c Surrounding wall temperature =250 c…

An ice-skating rink is located in an indoor shopping mall with an environmental air temperature of 22-C and radiation surrounding walls of about 25-C. The convection heat-transfer coefficient between the ice and air is about 10 W/m2 - C because of air movement and the skaters' motion. The emissivity of the ice is about 0.95. Calculate the cooling required to maintain the ice at 0-C for an ice rink having dimensions of 12 by 40 m. Obtain a value for the heat of fusion of ice and estimate how long it would take e to melt 3 mm of ice from the surface of the rink if no cooling is supplied and the surface is considered insulated on the back side.

An ice-skating rink is located in an indoor shopping mall with an environmental air temperature of 22-C and radiation surrounding walls of about 25-C. The convection heat-transfer coefficient between the ice and air is about 10 W/m2 - C because of air movement and the skaters' motion. The emissivity of the ice is about 0.95. Calculate the cooling required to maintain the ice at 0-C for an ice rink having dimensions of 12 by 40 m. Obtain a value for the heat of fusion of ice and estimate how long it would take e to melt 3 mm of ice from the surface of the rink if no cooling is supplied and the surface is considered insulated on the back side.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.19P: 1.19 A cryogenic fluid is stored in a 0.3-m-diameter spherical container is still air. If the...

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A cooling system is to be designed for a food storage warehouse for keeping perishable foods cool prior to transportation to grocery stores. The warehouse has an effective surface area of 1860 m2 exposed to an ambient air temperature of 32C. The warehouse wall insulation (k=0.17W/(mK)) is 7.5 cm thick. Determine the rate at which heat must be removed (W) from the warehouse to maintain the food at 4C.
3.16 A large, 2.54-cm.-thick copper plate is placed between two air streams. The heat transfer coefficient on one side is and on the other side is . If the temperature of both streams is suddenly changed from 38°C to 93°C, determine how long it takes for the copper plate to reach a temperature of 82°C.
Heat is transferred at a rate of 0.1 kW through glass wool insulation (density=100kg/m3) with a 5-cm thickness and 2-m2 area. If the hot surface is at 70C, determine the temperature of the cooler surface.
A plane wall, 7.5 cm thick, generates heat internally at the rate of 105 W/m3. One side of the wall is insulated, and the other side is exposed to an environment at 90C. The convection heat transfer coefficient between the wall and the environment is 500 W/m2 K. If the thermal conductivity of the wall is 12 W/m K, calculate the maximum temperature in the wall.
2.38 The addition of aluminum fins has been suggested to increase the rate of heat dissipation from one side of an electronic device 1 m wide and 1 m tall. The fins are to be rectangular in cross section, 2.5 cm long and 0.25 cm thick, as shown in the figure. There are to be 100 fins per meter. The convection heat transfer coefficient, both for the wall and the fins, is estimated to be K. With this information determine the percent increase in the rate of heat transfer of the finned wall compared to the bare wall.
1.19 A cryogenic fluid is stored in a 0.3-m-diameter spherical container is still air. If the convection heat transfer coefficient between the outer surface of the container and the air is 6.8 , the temperature of the air is 27°C, and the temperature of the surface of the sphere is –183°C, determine the rate of heat transfer by convection.
3.17 A 1.4-kg aluminum household iron has a 500-W heating element. The surface area is . The ambient temperature is 21°C, and the surface heat transfer coefficient is . How long after the iron is plugged in does its temperature reach 104°C?
1.67 In beauty salons and in homes, a ubiquitous device is the hairdryer. The front end of a typical hairdryer is idealized as a thin-walled cylindrical duct with a 6-cm diameter with a fan at the inlet that blows air over an electric heating coil as schematically shown in the figure. The design of this appliance requires two power settings, with which the air blown over the electric heating coil is heated from the ambient temperature of to an outlet temperature of and with exit air velocities of 1.0 m/s and 1.5 m/s. Estimate the electric power required for the heating coil to meet these conditions, assuming that heat loss from the outside of the dryer duct is neglected.
2.2 A small dam, which is idealized by a large slab 1.2 m thick, is to be completely poured in a short Period of time. The hydration of the concrete results in the equivalent of a distributed source of constant strength of 100 W/m3. If both dam surfaces are at 16°C, determine the maximum temperature to which the concrete will be subjected, assuming steady-state conditions. The thermal conductivity of the wet concrete can be taken as 0.84 W/m K.
The furnace wall shown in the figure is made of a material with a thermal conductivity of 5 W / m ° C, the radiant emission coefficient of the outer surface of the wall is 0.95, Stefan Boltzman constant is 5.67x104 W / m ^ 2 (K ^ 4), ambient temperature and air temperature 297 K is. The heat transfer coefficient between the outer surface of the wall and the air is h = 20 W / m (K ^ 2). Wall inner surface temperature 573 K, outer surface temperature 308 K Since the value is kept constant a) Find the layer thickness of the wall? b) Find the layer thickness of the wall if the moving fluid medium on the outer surface of the wall is corroded?
A plane wall 20 cm thick with uniform internal heat generation of 200 kW/m3 is exposed to a convection environment on both sides at 50◦C with h = 400 W/m2 · ◦C. Calculate the center temperature of the wall for k = 20 W/m · ◦C.
An electric heater with the total surface area of 0.25 m2 and emissivity 0.75 is in a room where the air has a temperature of 20°C and the walls are at 10°C. When the heater consumes 500 W of electric power, its surface has a steady temperature of 120°C. Determine the temperature of the heater surface when it consumes 700 W. Solve the problem (a) assuming negligible radiation and (b) taking radiation into consideration. Based on your results, comment on the assumption made in part (a).