Heat pump Definition and 97 Threads

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) =...

I'm going a bit off the reservation to try something experimental when I attempt my own HVAC installation and I'm having some trouble determining a few things. I want to transfer heat from water flowing in a 3/4" copper tube that is submersed in a larger body of water. The copper pipe has a...

Homework Statement I just want to know when do I use the formula for COP refrigerator vs COP Heat pump. If the heat is absorbing something then what formula do I use Homework Equations [b]3. The Attempt at a Solution [/b} Uh I just trying 2 figure out the concept so Idk how 2...

Homework Statement If the temperature underground is 5 degrees Celsius and you'd like to keep the house at 20 degrees Celsius, how much work per joule leakage must be done to maintain the house at that temperature? Homework Equations Q/W = 1/(1-(Tc/Th)) The Attempt at a Solution I...

So, I've been thinking a lot on this lately. I want to use two turbochargers, one with just the compressor - and one with both compressor and turbine. Doing calculations at 10 deg C. Doing the math for Norway because commercially avatible evap heat exchangers doesn't really work well in our...

Question is attached I have spent a great deal of time on this problem and I am hoping someone can help me out. My attempt at problem. first for the heat engine QL/Qw1 = TL/Twaste so efficiency = 1- Tl/Twaste efficiency = 0.93808 and I know that efficiency = Wout/ Qw1 This is as...

A heat pump that used R-22 operates as shown below. Assume SEER=1.15*EER. Find the amount of work that has to be put into the system to generate 15,000kwh of heat energy.

Homework Statement A freezer has a coefficient of performance of 6.30. It is advertised as using electricity at a rate of 457kWh/yr. a)On average how much energy does it use in a single day? b) What maximum mass of water at 20.0 degree celsius could the freezer freeze in a single day...

let's say some amount of heat is absorbed by a refrigerant for phase change at a low pressure. will this heat absorbed be equal to the heat given out by the compressed refrigerant at high pressure? i know that the amount of heat required for phase change from liquid to vapour is less at low...

let's say some amount of heat is absorbed by a refrigerant for phase change at a low pressure. will this heat absorbed be equal to the heat given out by the compressed refrigerant at high pressure? i know that the amount of heat required for phase change from liquid to vapour is less at low...

I have a general question, it's not homework or anything, we are studying heat pumps and thermal efficiencies and COP. There's an example in my book that has a heat pump that is heating a house and it asks to find the minimum theoretical cost per day. Of course the solution and detailed steps...

1. You have a heat pump which has a coefficient of performance (C.O.P.) that is 17% of the maximum achievable. You want to heat your house to 20◦C. At what outside temperature does the heat pump become not useful? 2. C.O.P. = 1/(T1/T0 - 1) T1= Temperature of the outside...

We have a carnot engine with Th = 800 degrees Celsius, and Tc = 50 degrees Celsius. This produces a work which is drives a carnot heat pump which has heat reservoirs at Th' = 50 degrees celsius and Tc' = 0 degress Celsius. What is the ratio of heat absorbed by the Heat Engine to the heat...

Homework Statement A heat pump heats a house in winter by extracting heat from the cold outdoors and releasing it into the warm interior. for the transfer of a given amount of heat, (a) how do the entropies of the interior and exterior of the house change (increase or decrease) b)which...

Is it possible to create analog of a heat pump which would be able to concentrate potential energy of electrons in one place, using some work, so there would be gain in energy?

Homework Statement A house is heated by means of a carnot engine operating in reverse (Heat Pump). The outside Temperature (Tc) is 270k, and the required inside temperature (Th) is 300k. If heating the house to this temperature normally requires 10kW of electrical heating, how much power is...

Homework Statement A heat pump has a coefficient of performance of 3.70 and operates with a power consumption of 6.91 103 W. (a) How much energy does it deliver into a home during 1 h of continuous operation? 9.2x10^7 J (b) How much energy does it extract from the outside air? ? JHomework...

Introduction Lately, i have been attempting to develop a better understanding of thermodynamics, but i have encountered a few problems. I considered that endothermic solvation, (e.g. dissolving KNO3 in water) is essentially the same as an absorption heat pump. This idea was based on the...

I am researching ground source heat pumps, however I do not completely understand how they work. I understand that a pump uses a small amount of electricity to pump heated ground water or an antifreeze solution through the a system of piping in the ground to transfer heat from the ground to a...

please help me ,i have a project which i m not easy with can anyone help me in designing a a vapor compression cycle for cooling in the summer and if desired heating in the winter, and a ground source heat pump for cooling in the summer and if desired heating in the winter.

I am about to pour a concrete floor in an addition to my basement (about 13' x 24'). This room is adjacent to my electric water heater. I have bought a 9500 btu R-22 compressor which I plan to use to replace the electric element in my 50 gallon water heater. The condenser is the water heater...

Homework Statement A heat pump with COP of 2.5 is used to heat a house. When operating, the heat pump cosumes 8kW of electrical power. If the house is losing heat to the outside at an average rate of 40000 kj/h and the temperature of the house is 3 degree celcius when the heat pump is turned...

Hi, I'm doing a science project involving the energy required to run a heat pump for the average size automobile measured in watts. I've been going through sites like mad, but can't find anything helpful. can anyone give me an estimate, or better, a reference to a site with such data on it? I'm...

Homework Statement The question asks us to advise the company on a heat pump (and give reasons) which is claimed to deliver 1500J to a room at 280K by consuming 50J of work per cycle pumping heat from the surroundings at 270K. I've drawn a diagram of the heat pump, taking heat Q2 from a bath...

O.K. this is maybe a large question... I am trying to find out how much energy it would take to do the work of a heat pump compressor that would be required to heat a... let's say 10 ft. x 10 ft. room of a typical house. I know there are a lot of variable here... What I am trying to...

I've always been told that systems that involve a heat pump need to be designed for a delta T of about 10C, not the more usual 20C, apparently because the pump can't lift the temperature more than this. Is this correct, and why is this so?

is it possible to get a cold surface radiating more heat to a hot surface than the hot surface to the cold? 1. Homework Statement Find the net radiation between two surfaces per square metre,1mm apart one surface flat and the other sigsawed with valleys 100 mm across tops and 100mm deep...

Homework Statement An ideal (Carnot) engine has an efficiency of 50 % If it were possible to run it backward as a heat pump, what would be its coefficient of performance? Homework Equations COP = (TL) / (TH - TL ) The Attempt at a Solution no temperatures are given. I just...

I have been working on an idea for a new energy source that I would like to get some input on. I took physics in college about 10 years ago, so I have a general understanding of the concepts, but I am definitely not an expert on thermodynamics. Here is my idea: 1. Use a heat pump(ground...

I know the formulas for efficiencies e of heat pump (it is e<=Tmax/(Tmax-Tmin)) and refrigerator (e<=Tmin/(Tmax-Tmin)), where Tmax and Tmin are temperatures of warmer and colder (respectively) involved containers. These formulas make me puzzled, as efficiencies seem to be possibly bigger than 1...

Homework Statement Assume that you heat your home with a heat pump whose heat exchanger is at Tc = 2degrees celcius and which maintains the baseboard radiators at Th = 47 degrees celcuiys. If it would cost $1000 to heat the house for one winter with ideal electric heaters (which have a...

if everything emits radiation, if you can stop the radiation from a hot body to a cold one but let the radiation from the cold to the hot you would have a type of heat pump.if you had a sphere (the hot body )with a vacuum in it and a relativey small cold body in the middle perhaps the...

For those who don't know, I'm an HVAC engineer. From time to time, the issue of heat pump efficiency comes up. When picking a system, obviously efficiency (cost) is important, so we need to decide between, usually, heat pumps (air source) and gas for a small split system. The government has a...

Homework Statement Air conditioners operate on the same principle as refrigerators. Consider an air conditioner that has 7.00 kg of refrigerant flowing through its circuit each cycle. The refrigerant enters the evaporator coils in phase equilibrium, with 54.0 % of its mass as liquid and the...

Thermo --> Heat Pump, confirmation. Homework Statement A cooling unit for a fridge has a 100 W power input. Environment temperature is 298 K. The heat which enters the fridge due to defective isolation is 350 W. What is the minimal temperature the fridge can reach? Homework Equations...

1. A heat pump is being used to keep the temperature inside a house at 23 C, while the tmeperature ouside is -6.0 C. The heat pump is providing heat inot the house at the rate of 8.8 kW with a coefficient of performance of 5.6. A) What power input (in KW) is needed to run the heat pump? B)...

Hi, Is it more efficient to run a heat pump in a house 24/7 or turn it off at night time and during work. All the pros seem to say its more efficient running them 24/7 I can't understand that as there is more heat loss with the greater heat differential running it 24/7 Thanks Darren

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)...

Air conditioners operate on the same principle as refrigerators. Consider an air conditioner that has 7.00 kg of refrigerant flowing through its circuit each cycle. The refrigerant enters the evaporator coils in phase equilibrium, with 54.0% of its mass as liquid and the rest as vapor. It flows...

1. North vs. South. A heat pump is designed for southern climates extracts heat from the outside air, and delivers air at 20C to the inside of the houses. What is the average coefficent of performance of the heat pump: (Consider this to be a Carnot device) a) In the south where the average...

While in California – the land of air conditioners and swimming pools – I noticed a relatively easy freebee for air conditioners and heat pumps. First. for comparison and perspective, consider that geothermal transfer systems are now used to replace the condenser/evaporator coil in...

In a home heat pump, heat is absorbed from the Earth by a fluid circulating in buried pipes and delivered to the home interior. Suppose that the heat pump is 40% as efficient as a Carnot refrigerator. If the ground surrounding the pipes is at 5`C and the interior temperature of the house is kept...

A heat pump has a coefficient of performance of 7.05. If the heat pump absorbs 20 cal of heat from the cold outdoors in each cycle, find the heat expelled to the warm indoors. Answer in units of cal. I believe COP (heating mode) : 7.05 and COP = Qh/W Qc = 20 cal so I have to find Qh= ? cal...

I'm having real trouble understanding the working process of a heat pump. A liquid with a certain temp flows in a system and gets vaporized, then it is compressed so that pressure and temp increase. Then it is cooled by a substance with lower temp so that it becomes a liquid again, and this...

A perfectly reversible heat pump heats a building at 20deg from the atmosphere at 5deg. If the heat pump is run by an electrical motor whose efficiency is 80%, what is the cost of 1KWhr of heat supplied? (1KWhr of electricity is 6p) I am confused by this qn as I thought the efficiency, e =...

This question is killing me because I just can't seem to get it. A heat pump is used to heat a house in winter; the inside radiators are at T_h and the outside heat exchanger is at T_c. If it is a perfect (e.g., Carnot cycle) heat pump, what is K_pump, its coefficient of performance? Give...

Here's my problem: A heat pump cycle whose coefficient of performance is 2.5 delivers energy by heat transfer to a dwelling at a rate of 20 kW. a) Determine the net power required to operate the heat pump, in kW. b) Evaluating electricity at 8 cents per kWh, determine the cost of electricity...