What is Heat pump: Definition and 99 Discussions

A heat pump is a device used to warm and sometimes also cool buildings by transferring thermal energy from a cooler space to a warmer space using the refrigeration cycle, being the opposite direction in which heat transfer would take place without the application of external power. Common device types include air source heat pumps, ground source heat pumps, water source heat pumps and exhaust air heat pumps. Heat pumps are also often used in district heating systems.
The efficiency of a heat pump is expressed as a coefficient of performance (COP), or seasonal coefficient of performance (SCOP). The higher the number, the more efficient a heat pump is and the less energy it consumes. When used for space heating these devices are typically much more energy efficient than simple electrical resistance heaters. Heat pumps emit less greenhouse gas than furnaces burning natural gas, but those powered by microwaves or hydrogen are also low-carbon and may become competitors.

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1. US Split-Phase to EU Heat Pump Not Working

Hi, I've ordered and received an advanced heat pump from Jiangsu Micoe in Red China. It is a full inverter-driven air-to-Water heat pump, IOW the fan motor, compressor, etc, are all PWM driven. The power supply takes in line voltage and immediately converts it to DC for moderation by the...
2. Electric Heater vs Heat Pump: Efficiency for Heating Water to High Temperatures

I want to heat 10kg of water from 20C to 80C-90C with the lowest power consumption. One option I consider is to use an electric heater and the other option is to use a heat pump. Are heat pumps common for such an application? The calculated power consumption of the electric heater is 0.7...
3. B Heat pump as a heat engine that operates in reverse

The efficiency of a heat engine is calculated as ##\eta = |W|/|Q_h| = 1- |Q_c|/|Q_h|##. If this engine operates between the temperatures ##T_c## and ##T_h##, then Carnot's theorem states that ##\eta<\eta_C = 1-T_c/T_h##. This means ##T_c/T_h < |Q_c|/|Q_h|##. Now assume that the heat engine is...
4. Does a "heat pump" not spew HFCs like an "air conditioner"?

https://slate.com/technology/2022/07/inflation-reduction-act-climate-bill-manchin-heat-pump-solar-panels-electric-cars.html First, this text makes no sense as it seems to say that the problem with A/C can be solved by "shift[ing] hot air in". But then it also seems to say that a "heat pump" -...
5. I Maximizing Efficiency: Exploring the Possibility of Self-Running Heat Pumps

So heat pumps are an interesting thing which I've recently discovered, and it has led to curiosity about how they work and what you can do with them. I hope to make my own property at some point, so a heat pump will doubtless come up then as I would like it to be an eco-home. Ground source heat...
6. MATLAB Modelling a Heat Pump with Linear Compressor using MATLAB Simulink

Hello, I am a final year mechanical engineering student designing a heat pump with a linear compressor for an electric vehicle and have decided to model this using Simulink, I would love some help on the governing equations/formulas needed for each component of the heat pump as well as guidance...
7. B Lorenz COP of a heat pump and the temperatures of the hot/cold reservoirs

@Dale : “The COP of a heat pump and the efficiency of a heat engine both depend strongly on the temperatures of the hot and cold reservoirs. For this calculation you need to go back and check the sources for the temperatures corresponding to each of these numbers. You will find that the Stirling...
8. B Can a Heat Pump and Stirling Engine Create a Perpetual Energy Cycle?

I was reading about heat pumps and it made me wonder… would the following process be physically possible…? I attach the hot side of the heat pump to the hot side of the stirling engine. 400% COP (coefficient of performance) means 1 kilowatt hour of electricity consumed by the heat pump delivers...
9. Question about Refrigerants used within a Heat Pump

I've been given the following 2 questions (please see below), and I've been asked to come with answers and arguments for my decision for the proposed answer, since there is just 1 correct answer per question. (so you can see my attempt below) Q1)The refrigerants have to: a)Vapourise at high...
10. Heat pump efficiency calculations - Compressor power issue

The heat pump comprises of the 4 components: evaporator, compressor, condenser and expansion valve. Thermal power required to heat the building: 12.1 kW at condensing temperature tc = 44.3 deg C For the evaporator: vaporizing temperature tv = -7 deg C Subcooling temperature for the heat pump Δ...
11. Peak Amps of a heat pump based AC vs compressor based AC?

In my city (USA) typical older houses have "100 Amp service" so their peak electric usage is limited to 100 Amps. In considering what sort of electric air conditioning system to install in such a house, peak usage is major consideration. Generally speaking, which type of residential unit...
12. Solve Heat Pump COP Equation with Q & T

I have tried to solve this with these equations: COP=T(H)/( T(H)-T(L) ) and COP = Q(H)/ ( Q(H)-Q(L) ) But since I need both Q and T in the same equation, I can't find anything to solve it.
13. I don't know how I got "mysterious energy" in a Carnot heat pump

So first I transformed the equation no 2 like this: $$|Q_L|=K\cdot|W|$$ And then I transformed the first equation to find ##|Q_Z|## $$|Q_L|=|Q_H|-|W|$$ Plugging the result into the first equation $$|Q_H|=K\cdot |W|+|W|$$ $$|Q_H|=|W|\cdot (K+1)$$ We know that the efficiency coefficient K is...
14. Pulling a vacuum on a heat pump with a recovery machine

I am a student attending an HVAC program at a trade school. Today I recovered refrigerant out of a heat pump in order to debraze the compressor out of the heat pump. My instructor has taught me how to use a recovery machine to recover refrigerant out of an air-conditioner or heat pump before...
15. Does a good heat engine make a bad refrigerator?

Hi all, the efficiency ##\eta## of a generic heat engine working between two temperatures is bound from above by the efficiency ##\eta_{\rm C}## of a Carnot machine working between the same temperatures. That is, if the temperatures are the same, a (ideal) Carnot machine is better than any...
16. Can a defective DRC on a heat pump cause the fan motor to go bad?

I noticed that the outdoor fan on my residential, split-system heat pump stopped working in mid-October. I don't know for sure exactly when my outdoor fan on my heat pump stopped working. It might be that my outdoor fan did not work for months before I noticed that the outdoor fan did not work...
17. Why does the outdoor fan on a heat pump need to run on heat mode?

The outdoor fan on heat pumps always runs when the compressor is pumping refrigerant when the heat pump is in heating mode unless the heat pump has defect(s). I don't understand why the outdoor fan on a split system heat pump needs to run when the heat pump is in heating mode. When a split...
18. Heating efficiency of a Heat Pump and a Space Heater

Homework Statement Instead of pumping heat into the cabaret air from the outside air, you could simply put an electric space heater inside the cabaret. A space heater turns electrical energy directly into thermal energy. Why would operating a space heater consume more electric power than...
19. Minimum consumption rate of a heat pump

Homework Statement Homework EquationsThe Attempt at a Solution Effiency of a heat pump is given as ## \eta = \frac { T_h }{T_h – T_c} = 30 ## W * 30/s = 6000*4.2 cal /s Minimum consumption rate = W/s = 840 watt Is this correct?
20. Why can the efficiency of a refrigerator (heat pump) be greater than one?

In a heat engine thermal energy is converted into mechanic energy. In a heat pump or refrigeration cycle - fluid is being circulated between hot and cold wells. But how can the efficiency be greater than 1? Is it because COP_{\text{heating}}>COP_{\text{cooling}}
21. What does the T-S diagram look like for an ammonia heat pump?

I'm a bit confused as to what the Temperature-Entropy diagram looks like for an ammonia heat pump. I understand perfectly how a freon type of refrigerant heat pump works: starting with working fluid at a state of a low-Temperature & high-Entropy gas (which is at low pressure), do work on the...
22. Why should a heat pump receive low return temperature?

One is always told that a heat pump (heating water) should receive return water with a temperature as low as possible. I've never really understood why. My initial thought is that if the return is higher, then it's "easier" for the heat pump to heat the water up to whatever supply temperature...
23. 2nd law of thermodynamics heat pump problem

Homework Statement Here is the problem: An inventor claims to have developed a heat pump that provides a 180 kW heating effect for a 293 K household while only consuming 70 kW of power and using a heat source at 273 K. Can this claim be possible? Homework Equations COP of heat pump = Qh/W COP...
24. Using heat pump to make a house heater

A heat pump in winter heat energy from the bottom of a lake, where temperature is 4 ° C and delivers thermal energy in a home where the temperature is 22 C. What is the theoretical minimum power the heat pump must be supplied to you at home must be able to take out 4000 watts heating power ...
25. Is a Heat Pump Clothes Dryer Worth the Investment?

The old tumble drier is past its use-by date and it is time to get a new one. The old one vents through a pipe to the outside and the new one will be a condensing type. I really can't think that they are efficient devices (efficiency in the loose sense, of course) as they seem to use the...
26. Refrigerator and Heat Pump question (Very Important)

Homework Statement Hi, How come, for a refrigerator and a heat pump, we don't consider the changes in energy for the refrigerant for when the pressure drops (at expansion valve) and when it rises (at the compression valve)? We only consider the changes in energy when it evaporates and...
27. Refrigerator and Heat Pump question

Homework Statement Hi. I know that a refrigerator and heat pump do the exact same thing, which is transferring heat from a cooler area to a warmer area. This is what I've gathered from my university notes. My question is: is it necessary for the area it's transferring FROM to be COOLER than the...
28. Can Variable Speed Heat Pumps Provide Different Temperatures at Different Loads?

Hi! The problem is in connection with variable speed heat pumps used for heating purposes, where the source/reservoir is ground/rock. The ground has temperatures around 5-7 celsius. Is it correct that these systems only can deliver one temperature at one load? E.g.: at 30 % of full power, it...
29. How to convert power to energy in a heat pump problem?

Homework Statement A heat pump fitted with a 120W electric motor supplies 600W of heat per second to a room from outdoors. Calculate: a) the coefficient of performance of the heat pump b) the heat gained from outdoors. Homework Equations Coeff of performance for heat pump = Qin/ W =...
30. Can a heat pump function without an evaporator and condenser?

I am a mechanical eningeer, designing a prototype for a system in which a heat pump moves heat between two process tanks with built in heat exchangers. I want to use an off the shelf heat pump but I want the process tanks to be the evaporator and condensor. If I buy a heat pump and bypass its...
31. Thermodynamics and conservation of energy

I have a question about conservation of energy in my system A heat pump allows you to move a quantity of heat with a smaller energy input. It is most efficient for small temperature differences. A heat engine allows you to convert a temperature difference into mechanical work. It is most...
32. Interpreting efficiency of heat pump

Hi everyone, I have a report to write for tomorrow and I am struggling with part of my conclusions. Essentially we have gained results from a heat pump as follows COP = 2.56 Carnot COP = 18.9 Energy Discrepancy = 0.015 Would anybody be able to help me interpret these results, ie are they...
33. Heat pump electricity production

Greetings. I just want to understand heat pumps. As far as I know - they keep a house warmer than it could be using a regular electric radiator, using the same amount of energy. I am wondering - if a heat pump outputs, say, 3 kW of heat energy from 1 kW of input electric energy from the grid (or...
34. Heat Pump Problem: Max Heat Transfer/COP Calculation

Homework Statement A)What is the coefficient of performance of an ideal heat pump that extracts heat from 11∘C air outside and deposits heat inside your house at 30∘C? B) If this heat pump operates on 2000W of electrical power, what is the maximum heat it can deliver into your house each hour...
35. Heat Pump Power and COP: How Does Temperature Affect Efficiency?

So if we start with question a) to calculate P = Q/t we can use that Q=m*c*ΔT so for for the 10 liters of water in the hot reservoir we get P=10*4186*25.8/1616=668 W. However it says the answer for a) is 667 W. Any idea why the difference? For question b) we have Vf = Pout / Pin where Pout =...
36. Where Does the Energy Go in a Heat Pump?

So, I understand that a heat pump to move heat from cold to hot requires some sort of energy to be added to the system. What happens to this energy? Is it just added to the output heat? I believe it must be, but I am not sure.
37. Reversing the Role of a Great Engine: Refrigerator or Heat Pump?

Reverse of a great engine is refrigerator or heat pump?
38. Refrigeration - Work required to run heat pump

This question has got me quite confused, some guidance would be really appreciated. A room is to be kept at 23C using a heat pump from ambient. Heat gain to the room is 1.5kW per degree Celsius difference between the atmosphere and the room. 1) If the outside temperature is 32C, what is the...
39. Reversible heat pump - Work input?

1. An ideal heat engine (HE) is used to drive a reversible heat pump (HP) as shown in figure below. The HE takes in Q1 heat units at T1 and rejects Q2 at T2. The HP abstracts Q4 from the sink at T4 and discharges Q3 at T3. Develop an expression for the ratio Q4/Q1 in terms of...
40. Geothermal heat pump or heat engine power requirements

Homework Statement In winter, you like to keep your house interior at 21.0 degrees C. Your geothermal heating system, which was advertised as being reversible, draws thermal energy from an underground reservoir at 347 K. In a cold winter, with the average outdoor temperature being 0.0...
41. Heat pump supply and return temperatures

A building is to be heated by radiators using an air-water heat pump. While radiators are not the ideal choice, it's beyond my decision making. Naturally I want the supply temp. to be as high as possible, hoping for 55°C in order to keep the physical size of the radiators to a minimum. As low...
42. Heat Pump COP: Air-to-Water Explained

The COP of a heat pump can be expressed as COP_{heating}=\frac{T_{hot}}{T_{hot}-{T_{cold}}} As higher is better, the value of this can be improved by reducing the temperature gap at which the system works. I'm just a little unsure about which temperatures are being talked about. The heat pump...
43. Saving Electrical Energy with a Heat Pump: 75%

Homework Statement The electrical energy supplied to a heater can be turned with 100% efficiency into thermal energy (room heating).Assume you use a heat pump with a COP of 4 instead to reach the same temperature increase in the room.How much electrical energy will you save ? Homework...
44. Misc. DIY Reverse Heat Pump: Cool a Room with Refrigerant

I don't know much about the subject, besides some diagrams and youtube vids, so please bear with me. I'm trying to make a reverse heat pump to cool a small room. If I had a heat reservoir (in a box within the same room) that could increase the temperature/pressure of a refrigerant and then...
45. Prove:β (heat pump) is always less or equal to β(Carnot HP)

Hello All! My professor in thermodynamics showed us the proof of the Carnot theory using integrals and a temp vs. entropy plot for a heat engine cycle. We haven't actually learned about entropy yet, so can someone help me understand how this translates into the coefficient of performance β...
46. Heat pump COP theoretical maximum

Hello everybody. I have trouble of proving the theoretical maximum of heat pump Coefficent of Performance. The thing I'm trying to calculate is for heat pump pumping heat from colder reservoir to the hotter reservoir: COP=Qh/W Qh - heat supplied to the hot reservoir(output) W - mechanical...
47. Heat Pump Design: Components & Assembly Guide

Hey guys, I'm looking at designing a heat pump system that uses CO2 as the working fluid. I'm not exactly sure how to pick the components that I need like a compressor, expansion valve, etc. I am trying to create an experimental device that will work in conjunction with my CO2 thermosyphon...
48. Heat Pump Efficiency in Cold Winter Months

I've been reading a lot, looking for ways to make my heat pump "work less" or more efficiently in the winter months. Since the HP transfers heat... in the winter it's 'taking' heat from outside and moving it inside.. supposedly heating my house. Would it be advisable or beneficial (both in out...
49. Is the Heat Pump and Motor Setup Efficient?

Not sure if I am doing this correct and do not have answer available... A heat pump takes on 30,000BTU/hr of heat and uses 5030 watts. However its COP as an air conditioner is 2.19. How efficient is the pump and motor setup? I am assuming the following: Qh=30000 BTU/hr=11.79 hp WKin=5030...
50. Heat pump problem with heat loss?

Homework Statement Consider a heat pump used to heat a house to 70°F when the outside temp is 5°F. The total heat loss from the house is 10000 BTU/hr. Efficiency of the heat pump is 45% of the theoretical maximum. What will be the power used by the pump? Homework Equations e (or cop) =...