Heat Pump

A note from Geoff Alder…

I have posted this file for RACA readers who have been following the “Our Industry” series on the pressure enthalpy diagram. In the RACA March 2007 issue, we discussed heat pumps. I invited interested readers to visit my Website to download this file, which is intended to explain a common arrangement of change-over system as may be used for heat pump application.

The graphics have been kept very basic to permit operation on any version (I hope)! of PowerPoint.

Here is an example of the valve type we have in mind…

Pilot valve

Solenoid coil 4-way valve.

In the animations that follow, ORANGE signifies high pressure hot gas. GREEN signifies low pressure suction vapour.

To open our discussion, here is an animation of the pilot valve in operation…

Pilot valve These are the small pilot lines.

G HOT AS

4 – WAY VALVE IN OPERATION

Incomers from pilot valve.

ION

SUCT

4-way valve.

Study the next two slides to see the full circuitry of a typical system for summer and winter operation.

SUMMER OPERATION Heat is rejected 4-way valve

Cooling being provided

WINTER OPERATION 4-way valve has now been switched.

Cold air is discarded

Heating being provided There will be some form of check valve change-over arrangement to alter capillary or restrictor characteristics to match for heating operation.

The following is the pressure enthalpy diagram from the article, which is the reason for this presentation.

This ends our mini-presentation.

View again?

I hope you found it useful!