# Tag Info

24

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 position gravity keeps the oil in the compressor. When we lay the refrigerator flat, some of the oil can leave the compressor and go into the cooling lines. The ...

17

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 pressure. When the spray valve is opened this pressure forces out the contents as an aerosol and more of the propellant evaporates as the internal pressure drops. ...

11

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 R134a has a NBP of about -26C. And dont use capital 'A' in R134a …. "A" denotes that the refrigerant is non -azeotropic. ResearchGate

11

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 the inside of the ice box cold. For premises not connected to the electric grid kerosene refrigerators were developed and are still available, kerosene ...

10

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 between interior and exterior). There are two ways that heat gets into the interior: Putting warm objects into the fridge. Heat leaking through the walls of ...

8

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 cooling systems, the cost of the entire system is greater than the cost of the labor and maintenance. Given mass manufacturing, though, it doesn't make sense to ...

6

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 you put bottles of water in your fridge it will take a lot more work by the fridge to cool them down than the equivalent volume of air as a litre of water at room ...

6

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 less to cool again. If you're not going to open the fridge, then it doesn't matter. As others have already pointed out, putting the water bottles in the fridge ...

5

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 through it. With direct sunlight the chassis heats up, the protective mesh on the fan heats up, surrounding walls and floors heat up from sunlight, the air passes, ...

4

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 can use the Carnot Equation to solve for your theoretical best efficiency. Once you know that, you deturmine what capacity you need. Like 2kW for example if I ...

4

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 end of the strip will close when the temperature is right - and the temperature can be tuned by turning a screw that pushes the strip closer or farther from the ...

3

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 the freezer. The temperature control from the fridge is sometimes nothing more than a slider that establishes how quickly the convected air moves. There are ...

3

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.

3

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 that's how you convert inches into metres. L's value is actually 1m. $$\frac{1000mm}{25.4mm} = 39.37$$ thus: $$39.37\frac{inches}{metre}$$ So the equation ...

3

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 entropy. With dryness fraction value and temperature combined, you can calculate the entropy of the refrigerant: $$entropy (s) = sf + x * sfg$$ Where: $\... 3 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 floor and warm air replaces it inside the fridge. If the doors are opened frequently, or held open for significant time, there is a lot of waste. On the other ... 3 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 while defining 1TR? Very little, if at all for the range of pressures likely to be encountered in air-conditioning applications where the term is used. Water ... 3 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" their inefficiencies. Why are they inefficient? Because the material they are made from ideally should have zero electrical resistance and infinite thermal ... 3 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 stack .My summation of the general answer is most aircraft AC is supplied by high pressure bleeds from the main engines not conventional AC compressors. The APU ... 2 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 units, but the answer needs to be in metric/SI, so you need to convert everything to SI units prior/during calculation. 1 inch = 2.54 cm = 0.0254 m 1/0.0254 = 39.... 2 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 a liquid state and cause hydraulic lock. Have not tested it myself as have always allowed plenty of time before turning it on - 5 hours or more... posted as an ... 2 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 where they are supposed to be. I am sure I didn't word it the exact same way but I am sure you get what I am saying. if it is on its side for 12 hours ... 2 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 condenser, i.e. the heat sink. If the system is completely enclosed, ie well-installed and well-fitted, it will not leak for many decades. This, of course, depends ... 2 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$is the internal cold temperature and$T_h$is the external hot temperature. Decreasing$T_h$will increase the CoP, meaning less work flow$\dot{w}\$ will be ...

2

Have you ever held your hand in front of a spray of atomized liquid from a can of liquid sprayer such as an air freshener? It's cold! Because the molecules of liquid have consumed heat energy of the same liquid to pick up acceleration. They convert pressure and heat to the kinetic energy of the streaming out spray molecules. The same thing happens in an ...

2

You can do this. I set up a sheet using vlookup to interpolate through fluid characteristics and because the source data I used (from steam tables) had a 5 degree increment I had to build an interpolation function using several vlookups / I will let you do that as it is good experience.

2

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 the modules, pumps, heat sinks and fans cheap and ignore your labor cost you may be able to come out at roughly the same manufactured cost a regular air ...

2

The refrigerant is chosen to match the internal temperature ie fridge or freezer or cabin and reject to above ambient. Above ambient is the same for all, but you idea fails as the internal temperature if a freezer at -18 deg C will not work firca fridge at about 4 deg C and do you want your cabin at -18 deg C? This is why you end up with separate systems and ...

2

To be able to run a freezer, the refrigerant must be colder than the freezer, so at most-10 degrees C or so. Such a temperature on an evaporator coil for regular HVAC would freeze the condensate and result in a non-functioning device (the coil would ice up). Also, a refrigeration cycle turns on and off according to the temperature. Placing two different ...

2

reciprocating pumps require lubrication, which inevitably injects oil mist into the outflow. This then has to be filtered out before the air enters the cabin. With a centrifugal compressor/blower, there is no oil mist in the airflow and no need for a demisting filter.

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