What is the minimum power required to operate the heat pump?

AI Thread Summary
To determine the minimum power required to operate a heat pump heating a house at 27 degrees Celsius with an outside temperature of -13 degrees Celsius and a heat loss of 7 kW, the efficiency equation e=Th/(Th-Tc) was applied, yielding an efficiency of 7.5. The calculated power requirement was 933 W, derived from dividing the heat loss by the efficiency. However, there was confusion regarding the units, as the heat loss of 7000 W should have been clearly indicated with units. Clarification on the equation's presentation and unit consistency was suggested to avoid misunderstandings. Accurate unit representation is crucial for validating calculations in thermodynamic applications.
swain1
Messages
30
Reaction score
0

Homework Statement


It is proposed to heat a house using a heat pump operating between the house (27 degees) and the outside (-13 degrees). The heat loss from the house is 7kW. What is the minimum power required to operate the heat pump?

Homework Equations


The Attempt at a Solution


e=Th/(Th-Tc) =7.5
W=7000/7.5 =933 W

Just checking if this is correct or have I made a mistake. Thanks
 
Last edited:
Physics news on Phys.org
Since you start out with a dimensionless number, a ratio of temperatures, and equate that to some number of Watts, something is surely wrong. Maybe you just need to rewrite things to make it clear
 
I have moved the equation now. If you look at the question you will see that 7000 has units of watts. Is it wrong anyway?
 
swain1 said:
I have moved the equation now. If you look at the question you will see that 7000 has units of watts. Is it wrong anyway?

That looks better. It woudl be better still if you had units of W on the 7000.
 
Thread 'Voltmeter readings for this circuit with switches'

Thread 'Voltmeter readings for this circuit with switches'

TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
View full post »
Thread 'Correct statement about a reservoir with an outlet pipe'

Thread 'Correct statement about a reservoir with an outlet pipe'

The answer to this question is statements (ii) and (iv) are correct. (i) This is FALSE because the speed of water in the tap is greater than speed at the water surface (ii) I don't even understand this statement. What does the "seal" part have to do with water flowing out? Won't the water still flow out through the tap until the tank is empty whether the reservoir is sealed or not? (iii) In my opinion, this statement would be correct. Increasing the gravitational potential energy of the...
View full post »

Similar threads

Heating efficiency of a Heat Pump and a Space Heater
Replies
1
Views
2K
Minimum consumption rate of a heat pump
Replies
5
Views
1K
Heat Pump Problem: Max Heat Transfer/COP Calculation
Replies
8
Views
5K
Using heat pump to make a house heater
Replies
2
Views
1K
Calculating Heat Exchange for a Water Pump
Replies
1
Views
1K
B Heat pump as a heat engine that operates in reverse
Replies
19
Views
4K
Heat pump problem with heat loss?
Replies
2
Views
2K
Reverse Carnot Engine (Heat Pump)
Replies
1
Views
3K
Geothermal heat pump or heat engine power requirements
Replies
8
Views
4K
Refrigerator- thermodynamics: how do i start?
Replies
1
Views
1K

Hot Threads

Recent Insights

Back
Top