Refrigeration system and a method for reducing the charge of refrigerant there in
In a given design of a refrigeration system, the present invention provides a method for reducing the charge of the refrigerant flowing through the refrigeration system. The refrigeration system includes a fluid conduit through which a flammable refrigerant circulates. The fluid conduit couples, in serial order, a compressor, a first heat exchanger, an expansion device, and a second heat exchanger. The conduit defines an interior diameter, an interior surface, and a given friction factor range. The method includes the steps of reducing the interior diameter of the conduit to thereby reduce the system design refrigerant charge, and coating the interior surface of the reduced diameter conduit with a coating composition to thereby reduce the surface roughness of the interior surface and provide a friction factor for the reduced diameter conduit that is substantially within the given friction factor range.
1 . In a given design of a refrigeration system, a method for reducing the charge of the refrigerant flowing through the refrigeration system, the refrigeration system comprising a fluid conduit through which a flammable refrigerant circulates, the fluid conduit coupling, in serial order, a compressor, a first heat exchanger, an expansion device, and a second heat exchanger, the conduit defining an interior diameter and an interior surface, the conduit defining a given friction factor range, the method comprising the steps of:
reducing the interior diameter of the conduit to thereby reduce the system design refrigerant charge, and
coating the interior surface of the reduced diameter conduit with a coating composition to thereby reduce the surface roughness of the interior surface and provide a friction factor for the reduced diameter conduit that is substantially within the given friction factor range.
2 . The method of claim 1 wherein the coating composition reduces the surface roughness to an equivalent sand grain roughness value of less than 0.0001 ft.
3 . The method of claim 2 wherein the coating composition reduces the surface roughness to an equivalent sand grain roughness value of between about 0.00005 and 0.000004 ft.
4 . The method of claim 1 wherein the reduced interior diameter is less than about 0.375 inches.
5 . The method of claim 4 wherein the reduced diameter is greater than about 0.0625 inches.
6 . The method of claim 1 wherein the coating composition coats the interior surface at a thickness of less than 0.200 inches.
7 . The method of claim 1 wherein the coating composition comprises at least one of polyvinylchloride, polyvinylchlor polyethylene, polypropylene, and polybutylene.
8 . The method of claim 1 wherein the coating composition comprises at least one of polyester acrylic copolymer, vinyl ester acrylic copolymer, bisphenol A polyester resin, polyester polyurethane polymer alloy, polyurethane resin, polyurethane acrylic blends, polyester reinforced polyethylene, and poly(vinylpyrrolidone).
9 . The method of claim 1 wherein the composition comprises teflon.
10 . The method of claim 1 wherein the composition comprises silicone rubber.
11 . The vapor compression system of claim 1 wherein the refrigerant is propane.
12 . The vapor compression system of claim 1 wherein the refrigerant is ammonia.
13 . In a given design of a refrigeration system, a method for reducing the charge of the refrigerant flowing through the refrigeration system, the refrigeration system comprising a fluid conduit through which a combustible refrigerant circulates, the fluid conduit coupling, in serial order, a compressor, a first heat exchanger, an expansion device, and a second heat exchanger, the conduit defining an interior diameter and an interior surface, the flow of refrigerant in the conduit having a given Reynolds number range, the method comprising the steps of:
reducing the interior diameter of the conduit to thereby reduce the system design refrigerant charge, and
coating the interior surface of the reduced diameter conduit with a coating composition to thereby reduce the surface roughness of the interior surface and provide a Reynolds number for the flow of refrigerant in the reduced diameter conduit that is substantially within the given Reynolds number range.
14 . The method of claim 13 wherein the refrigerant is a combustible hydrocarbon.
15 . The method of claim 13 wherein the step of reducing the volume of the fluid conduit includes reducing the interior diameter to less than about 0.375 inches.
16 . The method of claim 15 wherein the reduced diameter is greater than about 0.0625 inches.
17 . The method of claim 13 wherein the composition reduces the surface roughness to less than about 0.0001 ft.
18 . The method of claim 13 wherein the coating composition includes at least one of polyvinylchloride, polyvinylchlor polyethylene, polypropylene, polybutylene, polyester acrylic copolymer, vinyl ester acrylic copolymer, bisphenol A polyester resin, polyester polyurethane polymer alloy, polyurethane resin, polyurethane acrylic blends, polyester reinforced polyethylene, and poly(vinylpyrrolidone).
19 . The method of claim 13 wherein the coating composition includes teflon.
20 . The method of claim 13 wherein the step of reducing the friction factor includes coating the interior surface of the conduit at a thickness of less than 0.200 inches.
21 . A vapor compression system for use with a refrigerant, the system comprising:
a fluid circuit coupling, in serial order, a compressor, a first heat exchanger, an expansion device, and a second heat exchanger, said fluid circuit comprising a refrigerant conduit through which the refrigerant flows, the flow of refrigerant defining a Reynolds number (Re) of greater than 2000, the fluid circuit defining an interior surface, said interior surface coated with a composition, said composition providing said interior surface with a wall roughness of less than about 0.0001 ft.
22 . The vapor compression system of claim 21 wherein said conduit defines an interior diameter less than about 0.375 inches.
23 . The vapor compression system of claim 21 wherein said Reynolds number is between 2300 and 50000.
24 . The vapor compression system of claim 21 wherein said composition coats said interior surface at a thickness of less than 0.200 inches.
25 . The vapor compression system of claim 22 wherein said interior diameter is greater than 0.0625 inches.
26 . The vapor compression system of claim 21 wherein said coating composition comprises at least one of polyvinylchloride, polyvinylchlor polyethylene, polypropylene, and polybutylene.
27 . The vapor compression system of claim 21 wherein said composition comprises at least one of polyester acrylic copolymer, vinyl ester acrylic copolymer, bisphenol A polyester resin, polyester polyurethane polymer alloy, polyurethane resin, polyurethane acrylic blends, polyester reinforced polyethylene, and poly(vinylpyrrolidone).
28 . The vapor compression system of claim 21 wherein said composition comprises silicone rubber.
29 . The vapor compression system of claim 21 wherein the refrigerant is flammable and comprises hydrocarbons.
30 . The vapor compression system of claim 21 wherein the refrigerant is ammonia.