Systems and methods for supplying stored heat to a vapor compression system

A method of retrofitting an existing vapor compression system with an auxiliary heating loop having a thermal storage unit including a cavity filled with a plurality of particles, the vapor compression system including an indoor heat exchanger, an outdoor heat exchanger, and a compressor fluidly connected between the indoor and outdoor heat exchangers, the method comprising:

• fluidly connecting a first path of a first valve between the indoor heat exchanger and the compressor of the existing vapor compression system;
• fluidly connecting a first path of a second valve between the indoor heat exchanger and the outdoor heat exchanger of the existing vapor compression system;
• fluidly connecting a supply duct between the thermal storage unit and a second path of the first valve, wherein the thermal storage unit is operable at temperatures of up to 1200 F;
• fluidly connecting a return duct between a second path of the second valve and the thermal storage unit,
• fluidly connecting a defrost duct between the thermal storage unit and the outdoor heat exchanger;
• and
• fluidly connecting a defrost valve between the supply duct and the defrost duct, the defrost valve operable to selectively permit refrigerant to flow through the defrost duct, wherein the defrost valve is positioned in the supply duct,
• wherein the defrost valve is positionable to fluidly connect the outdoor heat exchanger to the thermal storage unit to permit refrigerant to flow in a defrost loop therebetween when in a defrost mode,
• wherein the second path of the second valve fluidly connects the outdoor heat exchanger to the thermal storage unit when in a defrost mode, wherein the refrigerant is diverted through the auxiliary loop in the defrost mode when the first valve is in a second position fluidly connecting the supply duct to the thermal storage unit and the second valve is in the second position connecting the return duct to the outdoor heat exchanger.

A controller for a vapor compression system including a primary loop and an auxiliary loop, the primary loop including an indoor heat exchanger, an outdoor heat exchanger, and a compressor, the auxiliary loop including a supply duct, a return duct, a thermal storage unit having a heating duct fluidly connecting the supply duct and the return duct, a defrost duct fluidly connected between the thermal storge unit and the outdoor heat exchanger, a defrost valve positioned within the supply duct and operable to selectively permit refrigerant to flow through the defrost duct, the thermal storage unit including a cavity filled with a plurality of particles, the thermal storage unit operable at temperatures of up to 1200 degrees Fahrenheit, the primary and auxiliary loops being connected by first and second valves, the controller comprising:

• a processor;
• and
• a memory storing instructions that program the processor to:
• operate the vapor compression system to provide a flow of refrigerant through the primary loop;
• determine if a condition has been satisfied by determining that a temperature of the outdoor heat exchanger has fallen below a threshold value;
• and
• adjust a position of the first valve to fluidly connect the supply duct to the outdoor heat exchanger and a position of the second valve to fluidly connect the outdoor heat exchanger to the return duct to and divert the refrigerant through the auxiliary loop when the condition is satisfied.