TR Calculation.

[AHU = air handling unit, a piece of equipment]

<what is the relation between cmh, cfm and TR.>

cmh = cubic metres per hour (a flow measurement)

cfm = cubic feet per minute (a flow measurement)

The above two are intimately related, being two ways of expressing the same thing.

TR = tons of refrigeration (a cooling duty power). 1TR = 3517.2 Watts. It isn't related to the other two unless more information is available, like some temperatures.

http://www.simetric.co.uk/si_c.htm

Is the TR specified for cooling coil of the unit is itself the TR of the equipment? what are the basic parameters required for calculating the TR of equipment and what are its formulaes???

Start with the temperatures.

Pasting below saved copy of answers from this thread. I am sorry I fogot to save the names.This is not mine and I'd not like to take credit.

As PWSlack mentioned, convert the btuhs into kw and you get your TR.

(Look for the Thread in Mechanical - it had something to do with heatting a warehouse or something)

For example if you had 1000 CFM of airflow that was delivering air heated 30 degrees, the heating would require:

1000 CFM x 1.08 x 30 degrees = 32,400 btuh (btu per hour)

Heating load is based on wall and roof conductive losses to the outside plus either infiltration or ventilation rates.

Infiltration rates are usually defined in air changes per hour. Ventilation to positively pressurize most buildings to avoid cold spots caused by infiltration requires roughly .05 cfm per square foot of floor space -- depending on the tightness of the building.

Assuming 20 foot ceilings, the internal volume is 3,400,000 cubic feet. Assuming the building is loose, being a garage, and experiences one air change per hour, that would be 56,667 cfm.

56,667 x 1.08 x 90 deg dT = 5,508,000 btuh

Heat loss through the walls and roof has to be considered. Assume roof insulation has an R factor of 24 and the walls are roughly 40,000 sq ft and have an R factor of 16. Heat loss through them would be:

170,000 * 90 deg dT/24 = 637,000 btuh

40,000 * 90 deg dT/16 = 225,000 btuh

Total maximum heat load would be 5,508,000 + 637,000 + 225,000 = 6,370,000 btuh

Heat generating devices within the space such as lights, motors, people, etc are not used when calculating maximum heating load. Similarly maximum heating load is assumed to occur at night so solar is ignored.

M as used in Mbtu means 1,000. It is the Roman numeral M for 1,000. 1,000,000 is represented as MM as in MMbtu.