Air-conditioning and Cooling technology Page 33

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Experimental set-up 1:

Measurement points:

Y = velocity, V = temperature, P = pressure, = humidity

Experiment goal:
Cooling - Surface cooling with dry cooling surfaces

Work plan:
Put a fan into operation (number of revolutions 100 %)
Put a refrigeration plant into operation
Open valve 1 and screen 3
Close valves 2 and 6
Relative humidity (measuring location: C, E)
Temperature (measuring location: C, E)
Velocity (measuring location: C, -)
- Enter measurement values in the table
- Enter conditions of air LC and LE in h-x diagram
- Identify the change of state with the connecting straight line
- Read the atmospheric density and enter it in the table
- Calculate the mass flow
- Determine enthalpy from h-x diagram
- Determine diverted heat quantity QK

Questions regarding findings:
1. Why doesn't water vapour condense on the cooler ?
2. Why does the change in conditions run parallel to the X line ?
3. Explain why the cooler temperature must be lower than the air temperature at measuring point E ?

1.: The temperature of the cooling surface is higher than the dew point temperature.
2.: Absolute humidity remains unchanged.
3.: Only part of the air has close thermal contact with the cooling surface. (Bypass effect).

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