Room temperature raises when the refrigerator left open why?

[RSAKTHIVEL]

Room temperature raises when the refrigerator left open why?

 

[schmitt trigger]

Because compressor based fridges are about 36% efficient, if I remember properly

For every thermal unit the fridge cools, it releases approximately three as heat. You have a net heat gain of around 2 thermal units.

 

[andre_luis]

The most thermal gradient on condenser, the most efficiency on dissipating its heat - according to Carnot postulation. Once you open the solenoid, the gas flux is bypassed from the capillary pipe, and all the heat took from compressor added to the heat from the intrinsic inefficiency of the system is accumulated.

 

[rahul.6sept]

Refrigerator works in the process in which heat flows from sink to source (surrounding environment) as per 2nd law of thermodynamics. Hence room temp rises when door of the refrigerator is left open.

 

[andre_luis]

I had assumed that @RSAKTHIVEL was referring to the fast defrost functionality available in some industrial refrigerators, once a priori the fact of a door be kept open or closed should not make any difference, once the surrounding room would heat anyway.

 

[c_mitra]

Room temperature raises when the refrigerator left open why?

The refrigerator is a net consumer of energy. This energy is finally dissipated as heat within the room. So the room temperature will increase whether the door is left open or not.

However, if the door is left open, the compressor runs continuously (because the thermostat fails to cool the room to the set temp) and the overall heating will be greater.

Engineers will recall that an ideal refrigerator is a Carnot cycle operated in reverse and you will need energy to pump heat from a lower temperature (inside the box) to higher temp (the room). All practical refrigerators are non-ideal and will need higher input of work to pump a given amount of heat from a lower temp to higher temp.

 

[andre_luis]

if the door is left open, the compressor runs continuously (because the thermostat fails to cool the room to the set temp) and the overall heating will be greater.

That's exactly the reason !

 

[c_mitra]

That's exactly the reason !

Well, if Q amount of heat is pumped from inside to the outside, with the door open, the source and sink are free to mix. All the energy input to the compressor is actually converted into heat, just like a heater. With the door closed, once the inside cold temp set is reached, the compressor goes off and heating of the outside will stop.

 

[andre_luis]

The point you cleverly touched and I wanted to highlight – regardless of efficiency aspects – is the continuous operation with the door opened, in opposition to the intermittent operation with the door closed.