Sorption heat pump and control method
A method operates an absorption heat pump system, specifically the flow of hydronic cooling fluid through the condenser during system start-ups, or when the cooling fluid temperature is low. To minimize the time for an absorption heat pump to reach full cooling or heating capacity, it is desirable for the high side pressure to increase as fast as possible, and the low side pressure to decrease as fast as possible. Since the high side pressure is a function of the temperature of the refrigerant exiting the condenser, if the condenser cooling fluid temperature is low, the corresponding high side pressure will be low, which may not permit adequate working fluid flow rates from the high pressure side of the system to the low pressure side.
1. A method of controlling a sorption heat pump comprising a condenser and absorber, the absorber and condenser being arranged in parallel with respect to the hydronic flow, the method comprising:
a) measuring the temperature of hydronic fluid entering or existing in the condenser; and
b) controlling a flow rate of the hydronic fluid entering the condenser in response to the temperature measured in a) to reduce the flow rate of hydronic fluid entering the condenser relative to a total possible flow rate and proportionally increase the flow rate of the hydronic fluid entering the absorber when the temperature is below a pre-determined value.
2. The method of claim 1 , wherein (i) reducing the flow rate of the hydronic fluid entering the condenser reduced relative to a total possible flow rate proportionally increases a flow rate of the hydronic fluid entering the absorber and (ii) increasing the flow rate of the hydronic fluid entering the condenser reduced relative to a total possible flow rate proportionally decreases the flow rate of the hydronic fluid entering the absorber.
3. The method of claim 1 , wherein the flow rate of the hydronic fluid entering the condenser is controlled by at least partially closing or partially opening a valve.
4. The method of claim 3 , wherein the valve is in a supply line supplying hydronic fluid to the condenser.
5. The method of claim 3 , wherein the valve is in a supply line supplying hydronic fluid to the absorber.
6. The method of claim 3 , wherein the valve is in a by-pass line that bypasses the condenser.
7. The method of claim 6 , wherein the by-pass line bypasses the condenser and supplies hydronic fluid to the absorber.
8. The method of claim 3 , wherein the valve is selected from the group consisting of an ON/OFF valve, a multi-position valve and a proportional valve.
9. The method of claim 3 , wherein the valve is closed for about 5 to about 20 minutes following activation of the heat pump from an off mode.
10. The method of claim 1 , wherein the flow rate of the hydronic fluid entering the condenser is reduced relative to a total possible flow rate for about 5 to about 20 minutes following activation of the heat pump from an off mode.
11. The method of claim 1 , wherein the pre-determined value is about 70 to about 90° F.