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[Chari]

This is regarding a water-cooled motor where air is the primary coolant and water acts as the secondary coolant, with a heat exchanger installed within the motor. I would like to understand the rationale behind limiting the water inlet temperature to 38°C and the water outlet temperature to 43°C.

 

My understanding is that the water inlet temperature is limited to maintain the primary coolant (air) temperature around 40°C, which aligns with the ambient temperature requirements set by the motor manufacturer. However, I'm unclear about the criteria for the water outlet temperature. To me, a higher water outlet temperature would indicate additional heat removal, which seems advantageous. So why is the water outlet temperature limited to a certain level.

Why only a temperature rise of 5°C? 

 

Below is the copy of datasheet:

Details of water cooling system

No. of cooler:1

Water requirement per cooler:490 LPM

Max. permissible temperature:38°C Of cooling water at inlet

Max. permissible temperature:43°C( 5°C rise) Of cooling water at outlet

Maximum permissible pressure At water outlet:6 Bar.

Water pressure drop through the cooler:0.4 kg/ sq.cm 

Temp. of cold air coming out & entering the machine for permissible cooling Water temp.:500C 

Temp. rise of air passing through machine at full load:30°C 

Air pressure drop through cooler:10 mm WC

Temp. rise of water through cooler:5°C

Protection against leakage of water:Water Leakage Detector.

Arrangement to ensure the water flow:Water Flow Indicator

 

 

[shvet1]

higher temperature rise => less water consumption => less velocity in tubes => higher residues precipitation => higher heat transfer resistance => higher risk of overheating at intermittent abnormal conditions or lack of maintenance

 

38°C inlet temp is just a handy figure as it is equal to 100°F wich has been widely spread in such sorts of calculations => there is a higher chance for a manufacturer to find some similar/equivalent device from a side project and therefore cut cost of design.