Refrigeration Definition and 87 Threads

Homework Statement Refrigeration system operates off Ref-134a. The refrigerant enters the compressor at 100kPa and -20C at a rate of 0.5 m^3/min, and leaves at 0.8MPa. The isentropic efficiency of the compressor is 78%. The refrigerant enters the throttling valve at 0.75MPa and 26C. It...

1. Homework Statement A refrigerator is to freeze 150g of water at 0°c in one minute, the ambient temperature being 20°C. Calculate in Watts the minimum power required? So known stuff: mass of water =0.15kg Temp of cold reservoir= 273k Temp of warm reservoir= 293k Specific heat capacity...

So I get that when the VP is equal to atmospheric pressure of 14.7 psia, if you will be at a saturated liquid and when more heat is added, it is latent head changing it to a gas. If however you are at a closed container where the can physically alter the "atmospheric pressure" in the container...

Estimate how long a time it will take to cool a trailer filled with coke ? Given the ambient temperature is 22 degrees C and heat transfer provided by the refrigeration unit is 10 kW and the drinkable temperature is 4 degrees C. Make reasonable estimates of how much insulation is included on...

i have calculated the coefficient of performance COP for both COP ideal and COP from p-h diagram. But the COP ideal i get is lower than the COP i calculated from p-h diagram. is it possible? please help :)

Consider a heat pump works on the vapor-compression refrigeration cycle with 0.2 kg/s of refrigerant-134a as the working fluid. The cycle is used to maintain a house at 26oC while absorbing heat from the outdoors at 3oC. R-134a enters the compressor at 200 kPa as a saturated vapor and leaves at...

The refrigerator at a house is driven by a vapor-compression refrigeration cycle shown in figure 6-19 in the textbook. Assume the refrigeration cycle is used to keep the interior of the refrigerator at -5oC at all times. When the kitchen’s temperature is 32oC, the refrigerator is estimated to be...

Homework Statement A glass manufacturer operates 11 months of the year and produces 97,000 tons of glass per year that needs to be cooled to ambient temperatures. The melting point of glass is 1673K and ambient temperature is assumed to be 293K. The specific heat capacity of glass is 0.837...

Hi guys, I have difficulties understanding the what I need to do in this problem. I have a ideal refrigeration cycle. first part is standard calculations, work of compressor and such. Results are Temperature range between -23 and 60 degrees C. Second part is the one that i do not understand. it...

Got a debate going on with some HVAC supertechs...One contends a sufficient quantity of non-condensables in a refrigeration system (vapor compression & med/hi temp application) will circulate "around" the system. He's saying with the "sufficient quantity", the liquid seal will be lost at the...

Homework Statement I have just done a lab with a refrigeration loop, and I'm unsure of which pressures correspond to which parts of the loop. The hand out says to assume the pressure across the condenser and evaporator are constant, and to use the two pressure guages to measure the pressure...

I know I can easily look this up on Wikipedia, but I chose to use my intuition on this one ;) Tell me if my intuition based approach is correct: You have a compressor which takes a refrigerant gas such as Freon and compresses/decompresses it. I'm imagining it works something like a piston in...

Hi, :smile: So I am learning about how refrigerators work. First I have to show the Carnot cycle and explain why it does not work in reverse - from my understanding, it does not. And then show how it actually works in real life, with the phase transitions, which I am guessing don't exist for...

So I can follow the sequence of operations: the refrigerant enters the compression stage as a saturated vapour(a gas?) and it's compressed raising the temperature of the refrigerant, it gives off some of this heat to the surrounding ambient air, causing a decrease in temperature and an according...

The attached file shows a T-s diagram of a refrigeration cycle . Now let us consider 2 refrigeration cycles as shown in the diagram 1-2-3-4 and 1'-2'-3'-4'. Which one will have a greater C.O.P or greater efficiency ? The first one (1-2-3-4) acts in a lower temperature range , whereas the 2nd...

Homework Statement What is the relationship between the heat absorbed and rejected by the reservoirs and their temperature. If a heat pump is used to transfer heat what is the rate at which heat is added to the hot reservoir in terms of the temperatures of the reservoir and the work done by...

Can someone please explain the picture attached below ? It has been taken from a lab where the supervisor actually failed to tell what is the remote sensing bulb doing attached to a condenser. I would like to know that why is it there and is the wire that is sticking out a capillary tube? If not...

Hi, has anybody worked with heat pumps? I'm recently confused about how the heat pump compressor operates. Does it have a fixed pressure or it actually adjust its pressure automatically to outdoor temperature variation? All my confusion originate from the following problem: Now we have a heat...

Hey, I am trying to determine the importantance and difference of fouling in sizing the evaporator and condenser in a Refrigeration cycle? Thanks, Alexisonsmith

im from India , in my third year of B.E. Mech degree .. course... and my group is planning to do steam jet refrigeration system...as a MINI PROJECT ( Design And Fabrication Project in the syllabus).. the components of the project are - 1. boiler 2. steam nozzle 3. thermocompressor 4...

Hello everyone, I am a first year engineering student and I am really interested in learning about refrigeration (this isn't homework its my own personal interest). I have done a bunch of research but I am a little confused on a couple of points and was hoping that you guys could help me...

Homework Statement Freon 13 is used as the refrigent in a commerical refrigeration process. At one point Freon 13 enters a heat exchanger at a pressure of 1 MPa and -25 degrees C. The liquid absorbs 115 KJ of heat per kg of Freon 13 entering the heat exchanger and exits at the same temp and...

Hello, I am a first year engineering student and I have a short question about refrigeration systems. Just want to clarify that this is not a homework question. Yes I do think about things like this in my spare time its just personal interest. I'm taking engineering for a reason :-p. Anyways i...

A 1.2 ton air conditioner has the capacity to freeze 2400 lb of ice at 0°C in a day. What is the equivalent rate of transport of heat in watts? QH(out)= QL(in) + Wi Coefficient of Performance= QL/ (QH-QL) Coefficient of Performance of an Ideal System: TL/ (TH-TL) QL/QH= TL/TH I...

I am NOT referring to laser cooling, the technique for supercooling atoms. The 1980 science fiction novel Sundiver by David Brin describes a kind of spaceship that could fly into the sun. One way described to keep the inside of the ship cool was to concentrate the heat inside the ship...

Hey guys, Just a bit stuck with getting enthalpy values off a table I have in a textbook. If we look at R-22 for example, the textbook gives me different answers than what is available on the net. If I use the values that are given to me on the net I get the correct value. The blue...

A practical question about that cycle: I've just bought a new fridge and looked at the refrigeration cycle for the first time in 5 or so years. Now, i feel that the condenser at the back is quite warm (as it should be) and is being cooled by my room. All good and well. But how does the...

Homework Statement Here is the cycle: I am to assume cold-air standard applies. I need to: a)Draw a T-s diagram b)Find where heat is transferred and work is done c)Calculate the coefficient of performanceHomework Equations COP = 1 / (TH/TL - 1) The Attempt at a Solution For the T-s...

I am doing a project for my thermodynamics class and we have to choose a compressor for a a vapor compression refrigeration cycle that has a heat transfer rate of 1500 btu/h and must maintain 0F in the freezer when the room temp is 90F. I have went through some calculations to find the mass flow...

Please look at the picture on this link of a refrigeration cycle: http://ffden-2.phys.uaf.edu/212_fall2003.web.dir/Dane_Lenaker/img/pics/frigcycle.gif Would the temperature at position 1 be the temperature leaving the evaporator or the temperature entering the compressor? or should they in...

:cry::frown::frown::cry: i am not getting what is the difference between a multistage refrigeration system and a cascaded refrigeration system. i know why staging refrigeration is used. 1# to achieve higher pressure ratio with two or more compressor or multi staging in compressors, thus...

Hey All Suppose ur designing a refrigeration cycle. if u go to the market to choose parts for an 18000BTU/h circuit. The compressor has different ratings according to the entering temp and exit temp, then u have the thermal expansion valve which is also rated in BTU/hr depending on entry and...

hi friends, I wanted to know about the Thermoacoustic Refrigeration.Can u please submit any links or explanation about the topic.Looking forward to your replies.

When a refrigerator has been turned on for some time, steady state refrigeration occurs. This is the normal refrigerator operative state. But what exactly happens? These things are really hard to do research on, since Internet searches, regardless of search query detailing, result in a lot...

I'm working on a project about cooling and heating, and have a couple of questions needing answers/clarification: Entropy in refrigeration: The pV-diagram for the phase change refrigerator is that of the reversed Otto cycle. This cycle contains two adiabatic and two isochoric processes...

Hey, I'm having a bit of trouble with a Thermo problem on a homework assignment. The problem is: 6-138 (Thermodynamics: An Engineering Approach, 5th Edition) The drinking water needs of a production facility with 20 employees is to be met by a bobbler type water fountain. The...

I'm sure most of you have heard of the Einstein Referigeration Cycle . For those who have not I've listed the references for further reading.. http://www.me.gatech.edu/energy/pubs/SLA_2.pdf ok 342 K is about 156 F ,for anyone with an attic , it seems to me that this is the perfect solution to...