Refrigerator Definition and 148 Threads

I'm confused about the wording "runs one-fourth of the time". My professor said we multiply the Q_L by four, but I don't get it conceptually.

I have a GE refrigerator( side by side ) about 11 years old now. I noticed warm milk yesterday. The set points for the freezer/fridge are 0 F and 37F respectively, and the actual temps are -7F and 55F. It seems like the freezer is running constantly, and the fridge side can get a word in...

The solution lists out mg(b/2)=ma(h/2) and then proceeds to solve for a. I am a bit stuck on how the initial equation is listed - why is the (b/2) swapped with the (h/2)? (namely, why isn't the equation mg(h/2)=ma(b/2)? My logic for this is y-direction and x-direction ) I feel that I am missing...

My refrigerator is on the minimal setting but still freezes the vegetables a little bit. It didn't do that a week ago. I'm renting and moving out in a few days so I'm not going to do anything drastic. How about wrapping my veggies in a blanket? I never understood the physics of those...

The answer key says the work done should be +.043cal. I am getting a negative sign. I have posted my work in the attached image. My logic is that since this a reversible engine we can say the integral of dQ/T=0. Looking at the cycle, Qc isi being absorbed (Qc>0) and Qh is being rejected...

I was just wondering if a mini fridge could ever work on electricity alone with no toxic chemicals inside?

I don't know where. to even begin inserting numbers here. I know the Temperature would be -5 for the first T and 36 for T sub zero but I do not know how to solve this. I never had Calculus.

If I orient my refrigerator such that the condenser coils at the back are facing a glass door (least insulation in room, cold outdoors) will CP increase? CP=Qc/(Qh-Qc) so Qh-Qc will be smaller thus CP larger. Could this damage refrigerator?

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There is this one problem from past exam papers which I cannot seem to do: The air in a kitchen has pressure 1.0 x 10^5 Pa and temperature 22'C. A refrigerator of internal volume 0.36 m^3 is installed in the kitchen. (a) With the door open the air in the refrigerator is initially at the same...

My teacher told me that answers are F=1200 N for lifting straight up and F= 360 N for using the ramp. I can get the force for lifting straight up by using 1800=F(1.5)cos(0) but I do not understand why for using the ramp the equation 1800 = F(1.5)cos(72.5) does not produce the correct answer.

Cooked some french fries last night using oil saved in the refrigerator. The oil appears to have undergone a phase change, after some time in the refrigerator instead of being a yellowish transparent liquid it was a semi-solid soft whitish non-transparent stuff when I took it out of the...

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...

I still confuse about COP of refrigerator. When i read some journal, it is said that COP of VCRS can be greater than 1 (usually 2 - 4). But, why the COP other than VCRS usally lower than 1? like vortex tube, vapour absorption refrigeration system, etc. Actually, now i am doing a research about...

I've been trying to understand how dilution refrigerators work and inbetween intermediate steps, between different temperature points, I see capillaries here and there under the name of impedances. After some googling, I somewhat convinced myself that it's to build up pressure before and after...

Hi, I want an expert opinion cause I've seached all web to no avail. I have an old fridge that can't start. Internet says this an overload protector problem because it tries to start then buzzes for exactly 10 seconds ( sounds like a locked rotor ) then a click is heard , it goes off for 2...

Homework Statement Suppose that heat leaks into your kitchen refrigerator at an average rate of 300W. Assuming ideal operation, how much power must it draw from the wall. Homework Equations \eta = \dfrac{T_C}{T_H - T_C} W= \dfrac{Q}{COP} The Attempt at a Solution A typical refrigerator...

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}}

I am trying to understand how refrigerator works from the thermodynamic perspective. I've read many articles and watched several youtube videos but still trying to figure out following stuff. 1. What exactly is the purpose of compressor? Ok it compresses vapor and thus increases it's pressure...

Homework Statement The pV-diagram in Fig. P20.51 (See attached file) shows the cycle for a refrigerator operating on 0.850 mol of H2. Assume that the gas can be treated as ideal. Process ab is isothermal. Find the coefficient of performance of this refrigerator. Homework Equations K = QC/|QH -...

Homework Statement I need to find the coefficient of a refrigerator that uses a monatomic gas and only has two steps. I know the: initial pressure of the refrigerant initial temperature initial volume and final pressure Every formula I know requires 4 steps or a knowledge of the outside and...

Homework Statement The door of a refrigerator is 1.5 m high, 0.80 m wide and 6.0 cm thick. Its thermal conductivity is 0.21Wm-1 degrees Celsius-1. a) what is the heat loss per hour through the door neglecting convection effects? b) Air is usually still inside the refrigerator so there will be a...

Hi all, I'm trying to find a special refrigeration device that can goes from -40 Degrees to 70 degrees. I need this machine for a laboratory to test sensors in differente temperatures. Does anyone knows where can I find something like that? Kind Regards Vicente

Hi all, I just want to throw some ideas and get feedback from the community on refrigerator door design. If anybody notices in supermarkets, etc, the frozen food are kept in glass-doored refrigerators. the prupose of the glass door is so the customers can see if the stuff they're looking is...

If I have a steady supply of isothermally compressed air at 7 psi (approximately 148 kPa) at a temperature of 4 degrees C, how would I calculate the amount needed of that air per unit time to maintain the temperature of a 14 cf refrigerator at 3 degrees C? A 18 cf freezer at -18 degrees C?

Homework Statement Show that the energy, E, that needs to be supplied to an ideal refrigerator to cool a mass M with specific heat C by \DeltaT from an initial temperature T_i is: E\sim \frac{MC\Delta T^2}{2T_i} Homework Equations Carnot efficiency where T_i is the starting higher temperature...

If a Carnot refrigerator requires a work input of only 230 J to extract 346 J of heat from the cold reservoir. Doesn’t this discrepancy imply a violation of the law of conservation of energy?

Anybody knows this book : The refrigerator and the Universe ? Is it any good ? And what is the level required to read it? Thanks

Homework Statement The following data refer to an electrically operated refrigerator: - Efficiency : ## \xi = 2.4## - Temperature inside: ##T_i = -9 ° C ## - Temperature of the radiator ## T_r = 40 °C ## - Room temperature: ## T_s = 35 °C## - Total surface of walls: ## A = 3.2 m ^ 2 ## -...

Homework Statement The temperature inside the room ##T_I= 25 C ## and the temperature outside the house is ##T_O = 32C##. The temperature difference causes energy to flow into the room (by conduction through the walls and window glass) at the rate 3,000 J/s. To return this energy to the...

I bought a couple of bar magnets at the local hardware store. They were acting so strangely. I couldn't figure out where the poles were. Finally I realized each magnet had four poles! They weren't quadropolar, rather half of each bar was magnetized one way and the other half the other way...

< Mentor Note -- Post edited > 1. Homework Statement So do you know how a microwave has air vents on the side? How much of a distance must be allowed between the vent and the side of refrigerator in order for the Microwave not to overheat? Is 10 cm enough? Would putting an aluminum foil on...

Homework Statement The coefficient of kinetic friction between a refrigerator and the floor is 0.20. The mass of the refrigerator is 100.0 kg, and the coefficient of static friction is 0.25. Determine the acceleration when you apply the minimum force needed to get the refrigerator to move...

A refrigerator in a hospital removes 40 kW of heat from a space used for blood storage. The coefficient of performance of the refrigerator is 8. What is the work (kJ) required to operate the refrigerator continuously for one day? What I attempted to do: W in = Qin/COP therefore, Win =...

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...

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...

Can we use same refrigerant for both air conditioner and refrigerator?

Homework Statement A refrigerator with a mass of 100kg measures 150cm high by 75 cm wide by 75 cm deep. How much force applied horizontally at the top edge of the front will make it start tipping backward? Assume that the center of mass is at the center of the refrigerator. Homework Equations...

Homework Statement Newton’s Law of Cooling. A building is maintained at temperature TH with a reversible heat pump operating between the building and a colder environment at temperature TC < TH. The heat pump consumes electrical power at a constant rate W. The building also loses heat...

I'm trying to keep my refrigerator cold when I have the door open and have read about putting water jugs in the back to help stabilize the temperature when the door is left ajar. Instead of water, would large aluminum heatsinks (with fins) work just as well? Thanks Don

I am a little confused, because I know how refrigerators work with a refrigerant and a compressor and heat exchanges, and I am looking to build one myself, just wondering because I was looking for refrigerator compressors online to buy. Do they have an inlet for refrigerant or is the...

Homework Statement I have a rectangular PV diagram of a heat engine. Like this one: I have to show why this cannot work in reverse as a refrigerator. Homework Equations U = 0.5fnRT (U = internal energy, f = degrees of freedom, n = number of moles of gas, R = ideal gas constant, T =...

Homework Statement You are trying to tilt a very tall refrigerator (2.0 m high, 1.0 m deep, 1.4 m wide, and 100 kg) so that your friend can put a blanket underneath to slide it out of the kitchen. Determine the force that you need to exert on the front of the refrigerator at the start of its...

I did attempt the problem, but I' now more confused than ever. Please help me. Joe is moving his refrigerator to take to college and he begins by pushing it across the wooden kitchen floor. On a flat surface like the floor, how do you calculate how hard he needs to push? Draw a free body...

Homework Statement A Carnot heat engine operates between temperatures T1= 400K and T2= 300K. In each cycle the engine receives Qin=1200 J from the high temperature reservoir. a) Calculate the heat Qout delivered to the low temperature reservoir. b) Suppose the engine is operated in reverse as a...

I understand that you need certain work for the refrigerator to work, and that it comes from the compressor. Why isn't a pump used instead? Why do you have to compress and heat the air so much? Thank you

Reverse of a great engine is refrigerator or heat pump?

Why is the boiling point of a refrigerant in a freezer lower than that of a refrigerator. I would think that a freezer needs more heat removed so the the refrigerant needs a higher heat of vaporization thus a higher boiling point. Thank you

Why temperature of refrigerator show higher than standard ? Which is the temperature standard should be below 5 degree of Celsius but it show 9 degrees

Let's say we have a long cylinder and two pistons inside the cylinder, and some vapour between the pistons. Now we make the pistons accelerate with some coordinate acceleration, along the cylinder axis, same coordinate acceleration for both pistons. Cylinder is static. Going to the frame of...