Frost-resistant year-round heat pump

Claim 2

A heat pump system comprising a refrigerant, expansion valve means, an evaporator, a condenser and a compressor, the evaporator being located so as to be subjected to an environment having varying temperatures, the heat pump system being coupled to extract heat from the enviroment via the refrigerant passed through the evaporator and to deliver extracted heat to the condenser, wherein the improvement comprises: the heat pump system extracting heat from the environment and delivering a substantially constant quantity of extracted heat to the condenser via the refrigerant substantially independently of the environment temperature as the environment temperature varies in a given temperature range, the evaporator having at lease three working sizes, the heat pump system including means for sensing a system parameter relating to a condition of the refrigerant inside the heat pump system, the heat delivered to the condenser being related to the condition of the parameter, and means for selectively coupling a working size of the evaporator in response to the sensed condition of the system parameter for operation in the heat pump system so as to maintain the system parameter substantially at a predetermined value and hence maintain the quantity of extracted heat delivered to the condenser substantially constant as the environment temperature varies in the given temperature range.

Claim 3

The heat pump system according to claim 1 wherein a substantial portion of the evaporator comprises continuous, plate-like heat transferring surfaces extending between the refrigerant and the environment operable to absorb sufficient environmental heat by conduction with a coating of frost or ice thereon to enable the heat pump system to operate in the given temperature range while the system parameter is maintained substantially at the predetermined value.

Claim 4

The heat pump system according to claim 1 wherein the system parameter is the suction pressure of the compressor, and wherein the sensing means senses the suction pressure of the compressor and the coupling means in response thereto couples a working size of the evaporator for operation in the heat pump system so as to maintain the compressor suction pressure substantially at the predetermined value in the given temperature range.

Claim 5

The heat pump system according to claim 1 wherein the system parameter is the pressure of the refrigerant leaving the evaporator, and wherein the sensing means senses the pressure of the refrigerant leaving the evaporator and the coupling means in response thereto couples a working size of the evaporator for operation in the heat pump system so as to maintain the pressure of the refrigerant leaving the evaporator substantially at the predetermined value in the given temperature range.

Claim 6

The heat pump system according to claim 1 wherein the system parameter is the electrical current demand of the compressor, and wherein the sensing means senses the electrical current demand of the compressor and the coupling means in response thereto couples a working size of the evaporator for operation in the heat pump system so as to maintain the electrical current demand of the compressor substantially at the predetermined value in the given temperature range.

Claim 7

The heat pump system according to claim 1 wherein the evaporator comprises a plurality of operating zones which in their totality provide an evaporator working size in excess of that which is required when the heat pump system is operating in an upper region of the given temperature range, and wherein the coupling means couples a number of evaporator zones for operation in the heat pump system in response to the condition of the system parameter sensed by the sensing means so as to maintain the system parameter substantially at the predetermined value.

Claim 8

The heat pump system according to claim 6 wherein the coupling means includes shutoff valves controlling the flow of refrigerant to the operating zones of the evaporator, the evaporator operating zones being connected in parallel and a separate shutoff valve being provided to control refrigerant flow to each zone, the coupling means operating the shutoff valves in response to the condition of the system parameter sensed by the sensing means so as to maintain the system parameter substantially at the predetermined value.

Claim 9

The heat pump system according to claim 7 wherein the expansion valve means comprises a plurality of individual expansion valves with at least one individual expansion valve being connected to each evaporator zone downstream of the respective shutoff valve.

Claim 10

The heat pump system according to claim 8 wherein the total capacity of the expansion valve or valves feeding one of the zones is different from the total capacity of the expansion valve or valves feeding at least one other zone, and wherein the expansion valve or valves feeding each zone have a capacity conforming to the working size of that zone.

Claim 11

The heat pump system according to claim 9 wherein the working size of each of the evaporator zones is a multiple of the working size of at least one other evaporator zone.

Claim 12

The heat pump system according to claim 7 wherein the expansion valve means comprises a single expansion valve disposed upstream of and feeding all of the shutoff valves.

Claim 13

The heat pump system according to claim 7 wherein the shutoff valves comprise electromechanical solenoid shutoff valves.

Claim 14

The heat pump system according to claim 6 wherein the operating zones of the evaporator each comprises one or more evaporator segments formed by continuous plate-like surfaces operable to absorb sufficient environmental heat by conduction with a coating of frost or ice thereon to enable the heat pump system to operate in the given temperature range while the system parameter sensed by the sensing means is maintained substantially at the predetermined value.

Claim 15

The heat pump system according to claim 13 wherein each of the evaporator zones contains a number of segments which is a multiple of the number of segments contained in at least one other evaporator zone.

Claim 16

The heat pump system according to claim 2 wherein the evaporator is mounted so that its working surfaces extend generally vertically.

Claim 17

The heat pump system according to claim 1 wherein the coupling means includes means for varying the setting of the value of the system parameter which is sensed by the sensing means at which it is to be substantially maintained.

Claim 18

The heat pump system according to claim 1 wherein the given temperature range exceeds 5° F., and wherein the coupling means couples an evaporator working size for operation in the heat pump system, and the heat pump system is operable, to extract heat from the environment and deliver a substantially constant quantity to the condenser as the environment temperature varies in the given temperature range exceeding 5° F.

Claim 19

A heat pump system comprising a refrigerant, expansion valve means, an evaporator, a condenser and a compressor, the evaporator being located so as to be subjected to an environment having varying temperatures, the heat pump system being coupled to extract heat from the environment via the refrigerant passed through the evaporator and to deliver extracted heat to the condenser, wherein the improvement comprises: the heat pump system extracting heat from the environment and delivering a substantially constant quantity of extracted heat to the condenser via the refrigerant substantially independently of the environment temperature as the environment temperature varies in a given temperature range, the evaporator having a variable working size, the heat pump system including means for sensing a system parameter relating to a condition of the refrigerant inside the heat pump system and outside of the evaporator, the heat delivered to the condenser being proportional to the condition of the parameter, means for selectively coupling a working size of the evaporator in response to the sensed condition of the system parameter for operation in the heat pump system so as to maintain the system parameter substantially at a predetermined value as the environment temperature varies in the given temperature range, the evaporator comprising at least three operating zones which in their totality provide an evaporator working size in excess of that which is required when the heat pump system is operating in an upper region of the given temperature range, and wherein the coupling means selects and couples for operation in the heat pump system a number of evaporator zones so as to maintain the system parameter substantially at the predetermined value, the expansion valve means comprising a plurality of individual expansion valves with at least one individual expansion valve being connected to each evaporator zone, the expansion valve or valves connected to each zone conforming to the working size of the respective zone, a substantial portion of the evaporator comprising continuous, plate-like heat transferring surfaces extending between the refrigerant and the environment operable to absorb sufficient environmental heat by conduction with a coating of frost or ice thereon to enable the heat pump system to operate in the given temperature range while maintaining the system parameter substantially at the predetermined value, the heat pump system thereby extracting heat from the environment and delivering the substantially constant quantity of extracted heat to the condenser in the given temperature range substantially independently of the environmental temperature and formation of frost or ice on the evaporator.

Claim 20

A heat pump system comprising a refrigerant, expansion valve means, an evaporator, a condenser and a compressor, the evaporator being located so as to be subjected to an environment having varying temperatures, the heat pump system being coupled to extract heat from the environment via the refrigerant passed through the evaporator and to deliver extracted heat to the condenser, wherein the improvement comprises: the heat pump system extracting heat from the environment and delivering a substantially constant quantity of extracted heat to the condenser via the refrigerant substantially independently of the environment temperature as the environment temperature varies in a given temperature range, the evaporator having a variable working size, the heat pump system including means for sensing a system parameter relating to a condition of the refrigerant inside the heat pump system and outside of the evaporator, the heat delivered to the condenser being proportional to the condition of the parameter, means for selectively coupling a working size of the evaporator in response to the sensed condition of the system parameter for operation in the heat pump system so as to maintain the system parameter substantially at a predetermined value as the environment temperature varies in the given temperature range, the evaporator comprising at least three operating zones which in their totality provide an evaporator working size in excess of that which is required when the heat pump system is operating in an upper region of the given temperature range, and wherein the coupling means selects and couples for operation in the heat pump system a number of evaporator zones so as to maintain the system parameter substantially at the predetermined value, the expansion valve means comprising a plurality of individual expansion valves with at least one individual expansion valve being connected to each evaporator zone, the expansion valve or valves connected to each zone conforming to the working size of the respective zone, a substantial portion of the evaporator comprising continuous, plate-like heat transferring surfaces extending between the refrigerant and the environment operable to absorb sufficient environmental heat by conduction with a coating of frost or ice thereon to enable the heat pump system to operate in the given temperature range while maintaining the system parameter substantially at the predetermined value, the heat pump system thereby extracting heat from the environment and delivering the substantially constant quantity of extracted heat to the condenser in the given temperature range substantially independently of the environmental temperature and formation of frost or ice on the evaporator.

Claim 23

The method according to claim 19 including the step of selecting the predetermined value of the system parameter at which it is to be substantially maintained, the minimum environmental temperature at which the system is operable being determined by the value selected of the system parameter and the particular refrigerant used.

Claim 24

The method according to claim 19 wherein the system parameter is the suction pressure of the compressor.

Claim 25

The method according to claim 19 wherein the system parameter is the pressure of the refrigerant leaving the evaporator.

Claim 26

The method according to claim 19 wherein the system paramenter is the electrical current demand of the compressor.

Claim 27

The heat pump system according to claim 19 including the step of selecting the capacity of the expansion valve means to correspond to the working size of the evaporator coupled for operation in the heat pump system.

Claim 28

The method according to claim 19 wherein the working sizes of the evaporator are provided in multiples of a smallest evaporator working size.

Claim 29

The method according to claim 19 wherein the evaporator has a plurality of working zones each of which is supplied with refrigerant through a separate expansion valve, the method including the step of providing expansion valve means for each evaporator zone having a capacity conforming to the working size of the evaporator zone it supplies.

Claim 30

The method according to claim 19 wherein the given temperature range exceeds about 5° F.

Claim 31

The method according to claim 19 wherein heat is extracted from the environment at an environmental temperature below about 32° F. via the evaporator and delivered to the condenser with a temperature available at the output of the condenser of at least about 90° F.

Claim 32

The method according to claim 19 wherein heat is extracted from the environment by the evaporator and delivered to the condenser in a temperature range of approximately 50° F. while the temperature available at the output of the condenser is greater than about 100° F.

Claim 33

The heat pump system according to claim 18 wherein the given temperature range exceeds about 5° F.