A thin, flat electric heater is exposed to air on both sides. On the top is a heat transfer coefficient of 20 W/m²-K and an air temperature of 20°C. On the bottom is a heat transfer coefficient of 10 W/m²-K and an air temperature of 10°C. If the power per area to the heater is 500 W/m2², what is the temperature of the heater?

A thin, flat electric heater is exposed to air on both sides. On the top is a heat transfer coefficient of 20 W/m²-K and an air temperature of 20°C. On the bottom is a heat transfer coefficient of 10 W/m²-K and an air temperature of 10°C. If the power per area to the heater is 500 W/m2², what is the temperature of the heater?

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 1.69P: The heat transfer coefficient between a surface and a liquid is 57 W/(m2K). How many watts per...

See similar textbooks

Similar questions

8.12 An electric room heater has been designed in the shape of a vertical cylinder 2 m tall and 30 cm in diameter. For safety, the heater surface cannot exceed . If the room air is at , find the power rating of the heater in watts.
If you have a room (10*7*3.5m) and you have 2 solar windows (the dimension of the window (2.5*2m)) located in the largest wall and the solar gain of them 1.5 kW/day and you have a door (1.6*2.5 m) in the northern wall and the temperature inside = 21°c and the average temperature outside = 10°C and the natural air change = 0.9 time /hour/day and the characteristics of materials are shown in the table below Elements U value Window 1.4 W/m.K Door 2.5 W/m.K South and North wall 0.5 W/m .K East and west wall 0.65 W/m .K Roof 0.45 W/m.K Floor 0.7 W/m .K If you know that you have 6 fixture lighting units of 50 W and the efficiency of them 70% and their runtime is 10 hours /day and there are 3 persons one of them is cooking and the two other are sleeping and they are present 4 hours/day and if you have the following appliance Appliance Running time Rotisserie 0.2 hour Large refrigerator 5 hours Blender 0.2 hour From your heat balance result decide if we will need a cooling or a heating system…
27
0.3MW / m3 heat is generated in a 6 cm thick flat wall. One surface of the wall is insulated and the other surface is exposed to an environment of 93C. The convection heat coefficient between the wall and the environment is 570 W / m2C and the heat conduction coefficient for the wall is 21 W / Since it is mC, calculate the maximum temperature (T0) inside the wall (C).
I just took a water bottle out of my refrigerator (0₁ = 3°C) and placed it on the kitchen counter. The environment is at 0₂ = 20 °C. The overall heat transfer coefficient between the bottle and the environment is 2 W/K and the heat capacity of the bottle and its contents is 3 kJ/K. Over what time periods would you consider the bottle to be an adiabatic system? A diather- Colar mal system?
An insulator has a thermal conductivity of 20 W/m ºC s used to separate two heat sinks whose temperature are 600 ºC and 300 ºC, respectively. What is the minimum insulator thickness to separate these two heat sinks when the maximum heat flux between them is 250 W/m2 ?
Consider you have conducted a lab work to analysis the system performance of an air conditioning system. Given that the refrigerant is R-134a. Table below shows the data collection on the 4 main sections of the system. Given that the heat loss from the compressor to the ambient is about 12 kJ/kg, and the ambient air temperature and the refrigerated space temperature are 36 °C and 10 C, respectively. Ignore the heat transfer in all the connecting lines between the components. Low Pressure 3.6 bar High Pressure 16 bar * Accuracy of the temperature measurement is about +1 °C T1 T2 T3 T4 10°C 75°C 44 °C 5 °C (a) Sketch a T-s diagram to show the above process. (b) Calculate the coefficient of performance (COP) of the refrigeration cycle. (c) Conduct the entropy analysis for each major component, and suggest a component that should be redesigned to improve the overall system performance. [2.678, Sgen4-1= 0.007635 kJ/(Kg K), Sgenl-2= 0.066885 kJ/(Kg-K), Sgen2-3= 0.041447 kJ/(Kg K), Sgen3-4=…
You want to heat a house on a very cold day as shown in the figure. To do this, you want to use photovoltaic panels as an energy source. It would be about using 15 panels each with an area of 1.5 m2. These panels would be connected to an electrical resistance that would heat the house as shown in the figure. The house is losing heat through the walls and ceiling as shown in the figure. The panels are receiving solar radiation at a rate of 800 W / m2 and if their efficiency is 15%. How much will the temperature of the house rise after an hour? The house is hermetically sealed. Assume that the specific heats of air, cv and cp, are constant as shown in the figure. sol = sun fuga = leakage aire = air
Please solve this problem THank you
A family enters a winter vacation cabin has been unheated for such a long time the interior temperature is the same as the outside temperature (00C). The cabin consists of a single room of floor area 4m by 4m and height 3m. The room contains one 2kW electric heater. Assuming that the room is perfectly airtight and that all the heat from the electric heater is absorbed by the air, none escaping through the walls or being absorbed by the furnishing, how long after the heater is turned on will the temperature reach the comfort level of 240C.
A solar collector and storage tank, shown in Figure (a) below, is to be optimized to achieve minimum first cost. During the day the temperature of water in the storage vessel is elevated from 25 °C (the minimum useful temperature) to tmax, as shown in Figure (b). The collector receives 260 W/m² of solar energy, but there is heat loss from the collector to ambient air by convection. The convection coefficient is 2 W/(m²*K), and the average temperature difference during the 10-hour day is (25 + tmax)/2 minus the ambient temperature of 10 °C. The energy above the minimum useful temperature of 25 °C that is to be stored in the vessel during the day is 200,000 kJ. The density of water is 1000 kg/m³, and its specific heat is 4.19 kJ/(kg*K). The cost of the solar collector in dollars is 20A, where A is the area in square meters, and the cost of the storage vessel in dollars is 101.5V, where V is the volume in cubic meters. Storage tank Collector (a) Temperature, °C tmax conforte 25°C, lowest…
A solar collector and storage tank, shown in Figure (a) below, is to be optimized to achieve minimum first cost. During the day the temperature of water in the storage vessel is elevated from 25 °C (the minimum useful temperature) to tmax, as shown in Figure (b). The collector receives 260 W/m² of solar energy, but there is heat loss from the collector to ambient air by convection. The convection coefficient is 2 W/(m²*K), and the average temperature difference during the 10-hour day is (25 + tmax)/2 minus the ambient temperature of 10 °C. The energy above the minimum useful temperature of 25 °C that is to be stored in the vessel during the day is 200,000 kJ. The density of water is 1000 kg/m³, and its specific heat is 4.19 kJ/(kg*K). The cost of the solar collector in dollars is 20A, where A is the area in square meters, and the cost of the storage vessel in dollars is 101.5C, where V is the volume in cubic meters. Storage tank Collector (a) Temperature, C tmax 25°C, lowest useful…