1. COMBINED CONDUCTION CONVECTION ON CYLINDRICAL WALL A hot-water pipe (k = 60 W/m K) in a house, made of 3/4-inch schedule 40 pipe (OD = 26.7 mm; thickness = 2.87 mm) is 15 meters long and contains water at 50 C. The air around the pipe is at 24 C. The heat transfer coefficient inside and outside the pipe are 1,135 W/m² K and 17 W/m²K, respectively. Insulation with thermal conductivity of 20 W/m K is to be added to the pipe. Determine the percent reduction of heat loss from the pipe due to insulation of 130 mm thick. hot water Qo air 24 C 50 C r2 BARE PIPE (w/o insulation) Q air insulation hot water pipe r2 ri PIPE with insulation

1. COMBINED CONDUCTION CONVECTION ON CYLINDRICAL WALL A hot-water pipe (k = 60 W/m K) in a house, made of 3/4-inch schedule 40 pipe (OD = 26.7 mm; thickness = 2.87 mm) is 15 meters long and contains water at 50 C. The air around the pipe is at 24 C. The heat transfer coefficient inside and outside the pipe are 1,135 W/m² K and 17 W/m²K, respectively. Insulation with thermal conductivity of 20 W/m K is to be added to the pipe. Determine the percent reduction of heat loss from the pipe due to insulation of 130 mm thick. hot water Qo air 24 C 50 C r2 BARE PIPE (w/o insulation) Q air insulation hot water pipe r2 ri PIPE with insulation

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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The heat transfer rate from hot air by convection at 100C flowing over one side of a flat plate with dimensions 0.1m0.5m is determined to be 125 W when the surface of the plate is kept at 30C. What is the average convection heat transfer coefficient between the plate and the air?
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.
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.
1.10 A heat flux meter at the outer (cold) wall of a concrete building indicates that the heat loss through a wall of 10-cm thickness is . If a thermocouple at the inner surface of the wall indicates a temperature of 22°C while another at the outer surface shows 6°C, calculate the thermal conductivity of the concrete and compare your result with the value in Appendix 2, Table 11.
Convection - Heat Transfer Coefficient (HTC) (1) The temperature of inner surface of insulation wall is t,=100°C, while the outer surface releases the heat by convection to surroundings air with temperature of -20°C. The thickness of the insulating layer is 5 cm and its thermal conductivity of 0,05 W/(m-K). What is the value of heat transfer coefficient on the outside this wall if its surface temperature t, is of 0°C.
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