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27 Nov 2019

To maintain the temperature inside a house at 20° C, theelectric power consumption of the electric baseboard heaters is30.7 kW on a day when theoutside temperature is -6° C.At what rate does this house contribute to the increase in theentropy of the universe?
1W/K

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Related textbook solutions

Physics: Principles with Applications
7th Edition, 2013
Giancoli
ISBN: 9780321625922

Related questions

As a engineer, you are designing a heat pump that is capable ofdelivering heat at the rate of 19 kW to a house. The house is locatedwhere, in January, the average temperature is −10°C. Thetemperature of the air in the air handler inside the house is to be43°C.

(a) What is the maximum COP for a heat pumpoperating between these temperatures?
1

(b) What must be the minimum power of the electric motor drivingthe heat pump be?
2kW

(c) In reality, the COP of the heat pump will only be 60 percent ofthe ideal value. What is the minimum power of the electric motorwhen the COP is 60 percent of the ideal value?
3kW

During 4 hours one winter afternoon, when the outside temperaturewas 11° C, a house heated by electricity was kept at 24° C with theexpenditure of 58 kwh (kilowatt·hours) of electric energy.

(a) What was the average energy leakage in joules per second(watts) through the walls of the house to the environment (theoutside air and ground)?

(b) The rate at which energy is transferred between two systems dueto a temperature difference is often proportional to theirtemperature difference. Assuming this to hold in this case, if thehouse temperature had been kept at 27° C (80.6° F), how many kwh ofelectricity would have been consumed?



In this problem you will estimate the heat lost by a typical house,assuming that the temperature inside is T(in) = 20*C and thetemperature outside is T(out) = 0*C. The walls have fiberglassinsulation, which dominates the heat conduction properties of thewall So we can consider the wall to have a thermal conductivity ofk(wall) = 0.048 W/m/K. We will take the thickness of the walls andceiling to be L(wall) = 12 cm. Assume that the house is a cube oflength L = 9.0 m on a side. Assume that the roof has very highconductivity, so that the air in the attic is at the sametemperature as the outside air. Ignore heat loss through theground.



a)What is H, the total rate of energy loss due to heat conductionfor this house?

b)Let us assume that the winter consists of 150 days in which theoutside temperature is 0*C on average. This will give the typicalnumber of "heating degree days" observed in a winter in Vancouver.Given that heating oil has an energy content of 35 MJ per litrewhen burned, how much oil will be needed to supply the heat lost byconduction from this house over a winter? Assume that the heatingsystem is 75% efficient.

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