Pregunta de entrevista

Entrevista de Mechanical Engineer Intern

-

Nokia

If you have a refrigerator in an isolated room (no heat in or out) and left the door to the refrigerator open, what would happen to the temperature to the room? Would it go up, down or say the same?

Respuesta

Respuestas de entrevistas

11 respuestas

20

The refrigerator will warm up the room. If you look on the back of the refrigerator, you will see metal grating. Touch it. Its warm! A refrigerator is transporting heat from the inside cavity to the outside. However, the power cord running from the wall is pumping energy into the refrigerator/room. Energy is powering the refrigerator. It is also running an irreversible process, the energy dissipates out as heat and work (mostly heat), making the net temperature of the room increase.

Someone who knows thermodynamics en

4

In this case, there is a net gain of energy from the refrigerator outlet into the room and no loss of energy out of the room. Thus, the room will warm up since there is a gain of energy.

Damian en

3

The temperature and overall heat content of the room will increase. Yes, the fridge it providing cooling, but it is doing this by removing heat from part of the air and dumping it into other parts of the air, all while doing work which is harnessed from the power input (electricity) from the wall. In other words, the heat in the air is just displaced from one area of air to another, so no loss nor gain of net heat, HOWEVER the work used to do this creates additional heat. If you consider this from a total energy standpoint, all energy within the room is fixed, except there's energy being added through the power input, so there's an increase in energy with time. I'm shocked at some of the other answers here, I hope those saying the temperature remains the same do not have mechanical engineering degrees.

Matt en

0

the temperature inside the room will increase

albert rios en

0

The room temperature will remain the same. The reason for this lies in its basic principle of vapor compression cycle. Its true that refrigerator transfers the heat from one place to another. But one has to remember that the door is open. So, As heat is extracted by refrigerant and thrown in room using condenser and since the room is isolated and refrigerator door is open.. the same heat will be added inside refrigerator and same refrigeration cycle continues after that. In a way refrigerator is not able to cool anything. it is just continuously maintaining energy equivalence.

rbawa en

0

Part of the room's temperature would decrease slightly. The other part of the room's temperature will stay the same. Since the refrigerator's energy is not large enough to cool the whole room it will cool a small portion of the room.

Anónimo en

1

Aa

Anónimo en

0

The room's temperature will be exactly as the refrigerator's temperature. Heat will be absorbed by the grating metal on the back of the refrigerator, so no need to worry about where the heat that refrigerator produces go.

Anónimo en

2

I propose the room remains constant - but for the following reason. The room is reported to be isolated. I denote that to be a cube with no walls, windows, doors, plumbing, OR conduit or an electrical box that would allow cable or air to move within or without the isolated cube. Logically, in that the fridge is not powered, it is not generating heat through the use of the motor, condenser or heat - exchange coils. Really, it doesn't matter what the answer is... you've just got to defend it logically. If the fridge were powered - but was an excessively large model (as you might find in a grocery store walk in) the room might cool. If it were a smaller unit - the motor would have to work overtime to try and keep it cool - thus heating the room. Just be creative! That's what they're looking for. Can you think on your feet.

Just another smarta$$ en

7

If the door to the refrigerator is left open, the frige has to work harder because now it has to try to cool the entire room rather than just the inside of the frige. The coils and condenser in the back of the frige would create more heat thus heating the room up.

Anónimo en

7

The temperature of the room would stay the same - the key is the fact that it is in an isolated room. There is no heat exchange between the room and it's external surroundings.

Anónimo en

Añadir respuestas o comentarios

Para publicar un comentario sobre esto, inicia sesión o regístrate.