Dual temperature heat pump system

Abstract

A heating system includes a heat pump that provides heat to a major fluid circuit and a minor fluid circuit for performing different heating operations. The system includes a power source having a variable cost and a controller configured to regulate flow of the major and minor fluid circuits to perform the heating operations. The controller is configured to receive information regarding the variable cost of the power source and distribute flow between the major and minor fluid circuits to perform the heating operations to minimize the electricity cost. The combined enhanced demand regulation and enhanced output regulation amplifies the total heat output and power consumption while permitting greater use of a power source of varying cost (e.g. PV)—thereby minimizing overall daily operating cost.

1 . A heating system comprising:
 a heat pump;   two heat output circuits in fluid communication with the heat pump for the flow of a refrigerant, the two heat output circuits comprising a major fluid circuit and a minor fluid circuit for performing different heating operations;   a power source having a variable cost; and   a controller configured to control the heat pump and regulate flow of the major and minor fluid circuits to perform the heating operations;   wherein the controller is configured to:   determine a variable cost of electricity of the power source; and   distribute flow as between the major and minor fluid circuits to perform the heating operations to minimize the electricity cost.   
     
     
         2 . The heating system of any of  claim 1 , wherein the controller is configured to maximize a fraction of daily time that is assigned to heating by the major fluid circuit such that average heat demand and changes of operating mode are minimized. 
     
     
         3 . The heating system of  claim 1 , wherein the controller is configured to maximize a fraction of daily heat that is delivered to the major and minor fluid circuits during defined periods within a day. 
     
     
         4 . The heating system of  claim 1 , wherein the power source comprises a photovoltaic thermal array that acts as a heat source to heat the refrigerant. 
     
     
         5 . The heating system of  claim 1 , wherein:
 the heat pump comprises an expansion device that expands the refrigerant, an evaporator for evaporating the refrigerant by the absorption of heat, an electric motor compressor for compressing the heated refrigerant, a desuperheater, and a condenser;   the major fluid circuit supplies cooling fluid for cooling the condenser; and   the minor fluid circuit supplies cooling fluid for cooling the desuperheater in contraflow heat exchange to the refrigerant.   
     
     
         6 . The heating system of  claim 1 , wherein:
 the major fluid circuit is configured to perform space heating of a heated space, and the minor fluid circuit is configured to perform a secondary heating operation; and   the controller is configured to maximize a fraction of daily time that is assigned to space heating by the major fluid circuit such that average heat demand and changes of operating mode between space heating and the secondary heating operation are minimized.   
     
     
         7 . The heating system of  claim 6 , wherein the minor fluid circuit includes a heat exchange coil within a hot water tank, and the secondary heating operation includes heating water in the hot water tank. 
     
     
         8 . The heating system of  claim 7 , further comprising a pre-heating thermal store arranged to pre-heat water before entering the hot water tank. 
     
     
         9 . The heating system of  claim 6 , further comprising a boost heater for supplementing heat output of the heat pump to the major fluid circuit for space heating. 
     
     
         10 . The heating system of  claim 1 , wherein the major fluid circuit comprises a major load circuit pump, a major load circuit flow temperature sensor, a major load circuit return temperature sensor, and one or more major load circuit heat emitters for emitting heat for space heating. 
     
     
         11 . The heating system of  claim 1 , wherein the minor fluid circuit comprises a minor load circuit pump, a minor load circuit flow temperature sensor, and a minor load circuit return temperature sensor. 
     
     
         12 . The heating system of  claim 1 , further comprising a source fluid circuit in thermal communication with the power source for providing a source flow of refrigerant to the evaporator. 
     
     
         13 . The heating system of  claim 12 , wherein the source fluid circuit further comprises a source fluid circulation pump for pumping the source flow of refrigerant to the evaporator, and a source circuit return temperature sensor measuring a temperature of the source fluid entering the evaporator. 
     
     
         14 . The heating system of  claim 1 , further comprising a user interface configured to receive user inputs from a user, wherein the user inputs include an indication of discomfort based on temperature within the heated space;
 wherein the controller is configured to create a profile for a minimum comfortable temperature level and a maximum comfortable temperature level based on the user inputs, and the controller controls the heat pump to perform the heating operations in accordance with the profiles for the minimum and maximum comfortable temperature levels.   
     
     
         15 . The heating system of  claim 14 , wherein the profiles for the minimum and maximum comfortable temperature levels respectively comprise a minimum temperature level and a maximum temperature level set for specified time intervals. 
     
     
         16 . The heating system of  claim 15 , wherein the user interface is configured to receive settings from a user that define user temperature preferences based on time, and the controller is configured to generate the profiles for the minimum and maximum comfortable temperature levels based on the user temperature preferences. 
     
     
         17 . The heating system of  claim 14 , wherein the user interface is configured to receive a user input including an indication of current discomfort based on temperature, and the controller is configured to control the heat pump to perform the heating operations in response to the indication of current discomfort. 
     
     
         18 . The heating system of  claim 15 , further comprising an outdoor temperature sensor for measuring an outdoor air temperature, and an indoor temperature sensor for measuring an indoor air temperature of the heated space, and the controller controls the heat pump to perform the heating operations further based on the outdoor and indoor temperatures. 
     
     
         19 . The heating system of  claim 18 , wherein the controller is configured to receive information regarding electricity cost of the system, and the controller controls the heat pump to perform the heating operations further based on the electricity cost information. 
     
     
         20 . The heating system of  claim 19 , wherein the controller is configured to:
 predict an outdoor temperature profile based on outdoor temperature information measured by the outdoor temperature sensor or internet weather data;   predict passive thermal gains of the heated spaced based on indoor temperature information measured by the indoor temperature sensor;   predict a marginal cost of electricity of the system based on the received electricity cost information;   predict user demand based on the user inputs to the user interface;   generate an optimized heat demand plan in accordance with the predictions, the plan being optimized for maintaining the temperature of the heated space within a comfortable temperature in accordance with the profiles for the minimum and maximum comfortable temperature levels while minimizing electricity cost; and   control the heat pump to perform the heating operations in accordance with the optimized heat demand plan.