26 votes
Accepted

What's wrong with transporting a refrigerator on its side?

After referring to some good online resources such this, I know why we shouldn't transport it laying down. Compressor is filled with oil which is critical to its operation. In the normal upright ...
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18 votes
Accepted

Why was Freon used in spray cans before it was declared a threat to ozone?

Spray cans work by containing a propellant which has a boiling point a small amount below room temperature. When the can is sealed the liquid and vapour reach equilibrium at a relatively modest ...
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12 votes
Accepted

What does "a" mean at the end of a refrigerant's designation (R-134a)?

R134a..Here "a" is used to denote that it is an isomer. R134 and R134a have same chemical formula and atomic weight but different chemical structures. R134 has NBP of about -19 C whereas ...
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  • 528
12 votes
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Why don't refrigerators have parts outdoors?

Electrical powered domestic refrigerators developed from ice boxes, also known as cold closets, which were tin or zinc lined insulated cabinets that had a ice compartment. As the ice melted it kept ...
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  • 9,382
10 votes
Accepted

Difference in energy consumption between empty fridge and fridge filled with bottles of water

The fridge works by pumping heat from its interior to its exterior. The amount of work it needs to do is proportional to the amount of heat entering the interior (and also the temperature difference ...
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  • 6,719
8 votes

Why don't refrigerators have parts outdoors?

The cost of installing and maintaining a split refrigeration system for cabinet style refrigerators would swamp the cost of the refrigerator itself. For large refrigerated rooms, or whole house ...
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  • 1,106
6 votes

Difference in energy consumption between empty fridge and fridge filled with bottles of water

There are two aspects to this. First if your fridge is filled with anything other than air then you will save the energy associated with cold air escaping whenever you open the door. However if ...
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6 votes

Difference in energy consumption between empty fridge and fridge filled with bottles of water

If you have unused space in the fridge, then it's better to fill it with something than to leave it air. This is because every time you open the door, less air will be exchanged with the room, so ...
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  • 11.2k
5 votes

Should we protect our AC's outdoor unit from sunlight?Does it increases the durability of an AC and its refrigerant if it is well shaded?

Direct sunlight increases power usage and wear of the unit. The cooling efficiency depends directly on temperature gradient - difference between temperature of the coolant and ambient air pushed ...
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  • 6,113
5 votes

How to size a refrigeration compressor based on an evaporator size?

When designing a refrigeration system, the first thing you need to know is the temperature you wish to heat/cool something to and the temperature of the source/sink you are pumping to or from. You ...
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  • 7,444
4 votes
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Thermostat design properties

A bimetallic strip is used. Two different metals like steel and copper expand at different rate and a strip of the two bound together as result bends with temperature changes. A contact placed at the ...
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  • 6,113
4 votes

Can Peltier Modules be practically used to cool a room?

Peltier thermoelectric cooling modules can be used to cool anything you like. It will not be economical compared to a standard off the shelf air-conditioner (R-134A compressor cycle). If you source ...
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  • 7,444
4 votes

Why are there no propane refrigerator air-conditioning units that run on solar heat?

It is a lot more efficient to convert the solar to electricity and run a decent heat pump for AC and normal refrigeration. Absorption refrigeration is expensive, bulky, not terribly versatile, and has ...
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  • 3,381
4 votes

Why are there no propane refrigerator air-conditioning units that run on solar heat?

This was my senior team project in engineering school, in 1974. Here were our findings: The power needed to run a small absorption refrigerator can be supplied by a solar collector of about 32 square ...
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4 votes
Accepted

Identify this textbook

Thermal Environmental Engineering 3rd Edition by Kuehn, Ramsey & Threlkeld (1998), Pearson.
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3 votes
Accepted

Store seeds at 1°C

The temperature control in a fridge is pretty crude. The evaporator is in the freezer and the compressor is controlled with an electric thermostat. The fridge portion however relies on convection from ...
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  • 7,444
3 votes

Should we protect our AC's outdoor unit from sunlight?Does it increases the durability of an AC and its refrigerant if it is well shaded?

An AC uses a large volume of air for cooling. Air in the shade is the same temperature as air in the sun. Yes sun will heat the outside of the unit but it will have a small effect on the cooling air....
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  • 479
3 votes
Accepted

Why divide the dimensions of a pressure vessel by 39.37 when calculating discharge capacity?

This is because of units. Getting the right answer with your units and their approach What the people have done in your question is converted everything to metres. The division of 39.93 is because ...
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  • 386
3 votes

How to find the entropy for a given temperature using P-H chart for a refrigerant?

Instead of giving you fish I will teach you how to catch it. There isn't a particular entropy at a given temperature. Considering the wet region there should be given a dryness fraction value for the ...
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  • 575
3 votes
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Relative inefficiency of doorless fridges at supermarkets

The doorless models (this was the photo in the question when I answered it) aren't as inefficient as they appear to be. Whenever someone opens a regular fridge door, its cold air pours out onto the ...
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3 votes
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1 Ton of Refrigeration

While defining 1 Ton of Refrigeration (TR), why doesn't some specific value of pressure come into definition? Isn't freezing water (to ice) related to pressure? If yes then why do we go away with it ...
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  • 7,479
3 votes
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Can a Peltier's device (i.e.Thermoelectric cooler) achieve cryogenic temperature efficiently?

There is no way to get around the physics in this case. The fundamental issue here is that peltier effect refrigerators are individually extremely inefficient, and stacking them in essence "stacks" ...
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3 votes

Why aircraft refrigeration uses a centrifugal compressor in place of reciprocating compressor?

I expect it is the capacity , large building AC units are also radial or axial ; smaller units are recips. And as commented , likely there is a weight advantage. I put this question in the Aviation ...
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  • 5,695
3 votes

Cooling system to maintain 0.5 °C at 95% humidity

At near-freezing temperatures, the amount of water vapor in the air to get 95% relative humidity is tiny, this is no problem. I recommend filling 55 gallon poly drums on pallets with water, park them ...
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2 votes

What does "a" mean at the end of a refrigerant's designation (R-134a)?

If a refrigerant contains 'a' at its end it is the isomer of that refrigerant. Example 'R123' is 'C2H2F3Cl2' and 'R123a' is the isomer of the same molecule.
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2 votes

Why divide the dimensions of a pressure vessel by 39.37 when calculating discharge capacity?

By dividing the diameter and length dimensions, which are in inches, by 39.37 you are converting them to metres. The problem you are trying to solve has inputs that are in both English and metric ...
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  • 9,382
2 votes

What's wrong with transporting a refrigerator on its side?

The theory is that the fluid can cause an air (well gas) lock that prevents the fluid moving around the system and the lack of fluid damages the compressor, or the fluid can get into the compressor in ...
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  • 13.6k
2 votes

What's wrong with transporting a refrigerator on its side?

I been told by a number a fridge maint. People Their rule of thumb is how ever long it lays on its side,, leave it upright that long before plugging it in . Will give oils time to drain back down to ...
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2 votes

Should we protect our AC's outdoor unit from sunlight?Does it increases the durability of an AC and its refrigerant if it is well shaded?

In this type, the rated power is determined in such a way that the outdoor unit is not in any way protected by shadows or shields; That is, the outer plate casing essentially casts a shadow on the ...
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2 votes
Accepted

Save money with using a refrigerator correctly - blowing cold air to the back of it?

Foundations The CoP of a refrigerator uses the cold heat flow and the work input, expressed as $\dot{q}_c / \dot{w}$. The Carnot expression based on temperature is $T_c / (T_h - T_c)$, where $T_c$ is ...
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