A room is initially at the outdoor temperature of 25°C. Now a large fan that consumes 200 W of electricity when running is turned on (Fig. 2–51). The heat transfer rate between the room and the outdoor air is given as Q · = UA(Ti − To) where U = 6 W/m2 ·°C is the overall heat transfer coefficient, A = 30 m2 is the exposed surface area of the room, and Ti and To are the indoor and outdoor air temperatures, respectively. Determine the indoor air temperature when steady operating conditions are established.

A room is initially at the outdoor temperature of 25°C. Now a large fan that consumes 200 W of electricity when running is turned on (Fig. 2–51). The heat transfer rate between the room and the outdoor air is given as Q · = UA(Ti − To) where U = 6 W/m2 ·°C is the overall heat transfer coefficient, A = 30 m2 is the exposed surface area of the room, and Ti and To are the indoor and outdoor air temperatures, respectively. Determine the indoor air temperature when steady operating conditions are established.

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 1.78P: What are the important modes of heat transfer for a person sitting quietly in a room? What if the...

See similar textbooks

Similar questions

The internal and external surfaces of a brick wall, 5m x 6m, 30 cm thick and with a thermal conductivity of 0.69 W/m·°C, are kept at temperatures of 20°C and 5°C, respectively. Calculate the rate of heat transfer through the wall (Figure 2), in W.
Determine the rate of heat loss from the pipe by natural convection, in kW. 18. An aluminum pan whose thermal conductivity is 237 W/m · °C has a flat bottom whose diameter is 20 cm and thickness 0.4 cm. Heat is transferred steadily to boiling water in the pan through its bottom at a rate of 500 W. If the inner surface of the bottom of the pan is 105°C, determine the temperature of the outer surface of the bottom of the pan.
The internal and external surfaces of a brick wall, 5m x 6m, 30 cm thick and with a thermal conductivity of 0.69 W/m·°C, are kept at temperatures of 20°C and 5°C, respectively. Calculate the rate of heat transfer through the wall (Figure 2), in W. find thermodynamic system borders and surroundings
The roof of an electrically heated house is 7 m long, 10 m wide, and 0.25 m thick. It is made of a flat layer of concrete whose thermal conductivity is 0.92 W/m·°C. During a certain winter night, the temperatures of the inner and outer surfaces of the roof were measured to be 15°C and 4°C, respectively. The average rate of heat loss through the roof that night was (a) 41 W (b) 177 W (c) 4894 W (d) 5567 W (e) 2834 W
The inner and outer glasses of a 2-m × 2-m double pane window are at 18°C and 6°C, respectively. If the 1-cm space between the two glasses is filled with still air, determine the rate of heat transfer through the air layer by conduction, in kW.
Question 1 Consider a large plane wall of thickness L = 0.4 m, thermal conductivity k = 2.3 W/m · °C, and surface area A = 20 m². The left side of the wall is maintained at a constant temperature of T1 = 90°C while the right side loses heat by convection to the surrounding air at To = 25°C with a heat transfer coefficient of h = 40 W/m? · °C. Assuming constant thermal conductivity and no heat generation in the wall: (a) Express the differential equation and the boundary conditions for steady one-dimensional heat conduction through the wall. (b) Obtain a relation for the variation of temperature in the wall by solving the differential equation. (c) Evaluate the rate of heat transfer through the wall.
A 2-kW electric resistance heater in a room is turned on and kept on for 30 min. The amount of energy transferred to the room by the heater is
1.)For heat transfer purposes, a standing man can be modeled as a 34.17-cm-diameter, 173.37-cm-long vertical cylinder with both the top and bottom surfaces insulated and with the side surface at an average temperature of 34.46°C. For a convection heat transfer coefficient of 14.33 W/m2 · °C, determine the rate of heat loss from this man by convection in an environment at 20.36°C. 2.)Consider a 1,499.74-kg car cruising at constant speed of 73.89 km/h. Now the car starts to pass another car, by accelerating to 111.73 km/h in 5.84 s. Determine the additional power needed to achieve this acceleration.
1. Consider a person standing in a room at 25°C. Determine the total rate of heat transfer and the heat transfer coefficient from this person if the exposed surface area and the skin temperature of the person are1.7 m 2 and 33°C, respectively, and the convection heat transfer coefficient is 5 W/m 2 · °C. Take the emissivity of the skin and the clothes to be 0.9, and assume the temperature of the inner surfaces of the room to be the same as the air temperature. (complete solution thank you)
Consider the base plate of a 1200-W household iron that has a thickness of L 0.5 cm, base area of A 300 cm2, and thermal conductivity of k 15 W/m · °C. The inner surface of the base plate is subjected to uniform heat flux generated by the resistance heaters inside, and the outer surface loses heat to the surroundings at T 20°C by convection. Taking the convection heat transfer coefficient to be h 80 W/m2 · °C and disregarding heat loss by radiation. Evaluate the temperatures at the inner and the outer surfaces. Resistance heater 1200 W Base plate Insulation 300 cm? T= 20°C h
The inner and outer surfaces of a 5-m × 6-m brick wall of thickness 30 cm and thermal conductivity 0.69 W/m·°C are maintained at temperatures of 20°C and 5°C, respectively. Determine the rate of heat transfer through the wall, in W
Consider a large plane wall of thickness L = 0.4 m, thermal conductivity k = 2.3 W/m · °C, and surface area A = 20 m2. The left side of the wall is maintained at a constant temperature of T1 =90°C while the right side loses heat by convection to the surrounding air at T∞= 25°C with a heat transfer coefficient of h = 40 W/m2· °C. Assuming constant thermal conductivity and no heat generation in the wall:(a) Express the differential equation and the boundary conditions for steady one-dimensional heat conduction through the wall.(b) Obtain a relation for the variation of temperature in the wall by solving the differential equation.(c) Evaluate the rate of heat transfer through the wall.