Cooling Coefficient & Heat Transfer Coefficient..?

These terms are meaningless unless more closely defined.

I am trying to understand the thermal design of Water cooled motors... Primarily heat generated in conductor, it passes through core, water jacket surface & water...

while studying i got cooling coefficient & Heat transfer coefficient words....

I did not got complete meaning of these words...

If someone know about these words, please explain with example & how it effects other parameters...

With regards..,

It would help if you could provide a quotation with those words used in context (along with a citation of the web page where they can be found).

For what's worth, I don't think they relate to COP for an HVAC system. More likely, I think at least the first has to do with the rate of heat flow (i.e., heat conduction) through a material.

Not sure if the two coefficients you are asking about are the same as coefficients of performance for heating/cooling, but when I read your question I thought of my thermodynamics course. Here is a link to a page describing COP's, it is not the same as what you are looking at just ignore my post

As Tornado indicates, a particular coefficient cannot be specified without context, however I can advise as follows:

The word coefficient in mathematical terms is a dimensionless scale factor that multiplies a relationship that has units and is often a ratio of two things.

So if heat is flowing though a solid substance according to 237 W·m−1·K−1

- which happens to be conductivity for Aluminium....

meaning 237 watts per (meter thickness times deg (Kelvin or Celsius))

then for that situation the coefficient is 237 and the units are watt, meter and deg K.

If other energy, distance or temperature units were used the value of the coefficient would be different for the same material.

In heat pumps the term CoP or Coefficient of Performance is used. In this case it is that ratio of energy output over the energy input. The units on both side of the equation should be the same and you will note that the coefficient value is different for heating and cooling for a given system.

Is it correct to say 237W/m/degC?. The area of cross section "A"m^2 through which the heat flows should be included. If area is bigger for same thickness and temperature difference you require more heat in watts

Coefficient of heat transfer is the rate of heat flow from one body to another. Final heat transfer is multiple of thermal conductivity of materials, surface area of contact, material thickness etc, whether in heating or cooling mode. Incase of water cooled motors, preferably use copper/aluminum tubes wound tightly over ribs for maximum body contact, flow water thru jacket at temperatures as low as possible, generally rejecting heat thru cooling towers. However, in case chilled water is available for very large motors, (above 100HP say), the water jacket will be insulated to prevent sweating & heat loss. Low water temperature will cool motor more efficiently

WEG make water cooled motors. They have a Bangalore office. Try calling them for explanation.

http://catalogo.weg.com.br/files/wegnet/WEG-water-cooled-motor-50026105-brochure-english.pdf

WEG Electric (India) Pvt. Ltd.
#38, Ground Floor, 1st Main
Road, Lower Palace Orchards,
Bangalore - 560 003

www.weg.net/in

CR4 Admin - email address and phone number removed

From the CR4 Rules: Do not post phone numbers or email addresses. The CR4 Admin will delete all phone numbers posted in threads or comments, and we strongly urge you not to put up email addresses. You can share this information via the CR4 internal messaging system.

Is it the "thermal conductivity"?.

Heat transfer coefficient is based on Newton's law of cooling for convection. It is not the property of the fluid. It depends on thermo physical or heat transfer properties of the fluids such as thermal conductivity, viscosity, density specific heat etc.

Thermal energy only travels in one direction. hot to Cold.

Heat transfer coefficient applies to both cooling and hesting processes. Cooling coefficient is heat tranfer coefficient for cooling processes only.