Question

URGENTLY NEEDED PLS HELP!!!

How does convection help a heat pump to operate more effectively ?

Answer 1

@Machida @joemc

Answer 2

Thermal energy is transferred from hot places to cold places by convection. Convection occurs when warmer areas of a liquid or gas rise to cooler areas in the liquid or gas. Cooler liquid or gas then takes the place of the warmer areas which have risen higher. This results in a continous circulation pattern. Water boiling in a pan is a good example of these convection currents. Another good example of convection is in the atmosphere. The earth's surface is warmed by the sun, the warm air rises and cool air moves in.

Answer 3

I hate to read it before lol

Answer 4

Conduction allowed the heat to spread through the coils. Convection is the fan blowing air over the coils.

Answer 5

@RANE Radiation too? :D

Answer 6

lol yes, this is y consider u as a gd friend, u can guess exactly wht i need to know next (at times) <3

Answer 7

Radiation is a method of heat transfer that does not rely upon any contact between the heat source and the heated object as is the case with conduction and convection.

Answer 8

Radiation involves electromagnetic radiation. An example of radiation is IR.

Answer 9

Yes, heat can be transmitted though empty space by thermal radiation often called infrared radiation. This is a type electromagnetic radiation . No mass is exchanged and no medium is required in the process of radiation. Examples of radiation is the heat from the sun, or heat released from the filament of a light bulb.

Answer 10

I just found this reference: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html#c2

Answer 11

bt then how does it clearly explains its relation with the heat pump ?

Answer 12

I do not believe radiation plays a role in a heat pump. The heat pump does work to move the heat. (We have not discussed this part of the process.) Conduction plays a role in moving the heat across the coils to be dissipated. Convection is when the heat is moved away from the coils by moving air.

Answer 13

bt it asks in my q' abt radiation as well

Answer 14

you can apply it.

Answer 15

mach u just repeated the same thing from above

Answer 16

Ya, you said with "heat pump"... thats there :3

Answer 17

The word radiation is sometimes incorrectly used. Think of the 'radiators' in cars for an example of this. They are called radiators, but no radiation comes from them.

Answer 18

what if that pump using sun-energy ???

Answer 19

like car sunlight-fuel energy

Answer 20

My imagination for pump by radiation system is like the car or phone that using sunlight-energy for fuel or battery. i think it can apply to pump.

Answer 21

Here is a reference for a heat engine:
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/refrig.html#c1

Answer 22

And more cycles are here: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatengcon.html#c2

Answer 23

mach can u say wht will u write if u had this q' to answer. wht would be your answer ?

Answer 24

@Machida

Answer 25

Q: How does radiation help a heat pump to operate more effectively ?

Answer 26

Radiation, as the term is used in a non-scientific setting, would be akin to convection. But, I would say that if we are using this for a P-chem setting, it does not play a role.

Answer 27

The matter is, we're not familiar with radiation on heat-pump. :/

Answer 28

Unless the heat pump is glowing red-hot, then radiation would be involved. But, if the heat pump is operating properly, this should not occur.

Answer 29

Let me look someplace and see what temperature this may become an issue at... (If I can find it...)

Answer 30

Okay,

Answer 31

I keep finding numbers for an ideal black body. This is most closely approximated by a hollow sphere with a blackened metal surface and a small opening....

Answer 32

oh my gd, this is so confusing

Answer 33

OK, got something in Atkins P-Chem...

Answer 34

In the chapter on Quantum theory...."A hot object emits electromagnetic radiation. At high temperatures an appreciable proportion of the radiation is in the visible region of the spectrum, and a higher proportion of short-wavelength, blue, light is generated as the temperature is raised."

Answer 35

The plot in the book is energy vs. wavelength for a number of temperatures. The lowest value plotted is 1250 K.

Answer 36

I also have a table in front of me in the 65th edition of the CRC Handbook. It lists radiation energy from a perfect blackbody at different temperatures.

Answer 37

A perfect black body would emit around 4.6K joules per sq meter per hour at around 370 K.

Answer 38

Sorry, meant to use ideal, not perfect. So, an ideal black body....

Answer 39

So, I would say that some quanta of energy is emitted via radiation (in the electromagnetic spectrum as photons). But, it is much than is dissipated via convection.

Answer 40

I suspect radiation is a very small percentage of the energy dissipated.

Answer 41

ok thank u so much