Heat transfer and storage system

A heat transfer and storage system for heating and cooling an enclosure, and including a heat pump having an indoor coil and an outdoor coil and a heat storage facility. The system can be operated to exchange heat between a refrigerant fluid from the heat pump and a heat transfer fluid from the heat storage facility, between the refrigerant fluid and ambient air, and between the heat transfer fluid and ambient air. In a preferred embodiment an integrated three medium heat exchanger is utilized in association with the outdoor coil of the heat pump and a water coil operatively connected to a water tank; and the three medium heat exchanger can effect heat exchange between the refrigerant and the water, between the refrigerant and outdoor air, and between the water and outdoor air.

BACKGROUND OF THE INVENTION 
This invention relates to a new and improved heating and cooling apparatus, 
and more specifically to a heat transfer and storage system utilizing a 
heat pump and a heat storage system such as a water tank and solar 
collector. 
Generally, a heat pump comprises a compressor, an expansion valve, an 
indoor heat exchange coil, an outdoor heat exchange coil, a refrigerant 
fluid, suitable refrigerant pipe line, and a refrigerant flow reversing 
valve. The heat pump has two sides; a low pressure side and a high 
pressure side. This pressure difference is caused by the compressor and 
expansion valve which also separate the two sides. One heat exchanging 
coil is located on one pressure side while the second coil is on the other 
side, and generally one coil is located inside an enclosure to be heated 
or cooled and the other coil is located outdoors. The reversing valve is 
used to reverse the direction of the flow of refrigerant through the heat 
pump which has the effect of reversing the pressure sides. Thus, at one 
time the inside coil can be on the low pressure side while at another time 
the outside coil can be on the low pressure side. Heat is absorbed by the 
refrigerant in the coil on the low pressure side and given up by the 
refrigerant in the coil on the high pressure side. 
Thus, a heat pump transfers heat between the indoor and outdoor coil 
depending on the position of the reversing valve. The heat pump can be 
used, for example, during cold weather to move heat from the outdoors to 
an indoor enclosure to warm the enclosure. At times when the outdoor 
temperature is very low a heat pump cannot transfer enough heat from the 
outdoors to the enclosure to satisfactorily warm the enclosure and 
requires supplemental heat such as electrical resistance heating. The 
system disclosed herein provides supplemental heat from inexpensive heat 
sources such as solar heat by utilizing a heat storage facility such as an 
insulated water tank to transfer heat either to the indoors directly or to 
the heat pump which then transfers the heat indoors. Heat can be put into 
the heat storage facility from the heat pump when it is convenient and 
economical to do so or from another heat source such as a solar collector 
and stored until needed. 
In addition to assisting a heat pump in heating an enclosure, a heat 
storage facility can also be used to assist the heat pump in cooling the 
enclosure. For example, if the temperature of the heat storage facility is 
lower than the temperature of the air surrounding the outdoor coil of the 
heat pump, then the heat pump can operate more efficiently if heat from 
the outdoor coil, which is the condenser coil when the heat pump is 
cooling the enclosure, is transferred to the heat storage facility than if 
the heat is transferred to the relatively warmer ambient air. 
The system disclosed utilizes an integrated three medium heat exchanger. A 
suitable heat exchanger of this type is disclosed in copending application 
Ser. No. 817,946 filed July 22, 1977 now abandoned in the names of David 
F. Wilson and Thomas E. Brendel. In a preferred embodiment the three 
medium heat exchanger is used to effect heat exchange between air, water 
from the heat storage facility, and refrigerant from the heat pump. An 
air-water refrigerant heat exchanger, when used with a heat pump, can 
improve the efficiency of the heat pump in several ways. For example, if 
the air-water-refrigerant heat exchanger is used in association with the 
outdoor coil of the heat pump, then when the heat pump is used to heat the 
enclosure and the outdoor coil functions as the evaporator coil the build 
up of frost on the evaporator coil can be eliminated. Also, an integrated 
unit has inherent advantages of low cost, minimum complexity, and 
compactness which are particularly desirable in systems designed for use 
in residential homes. 
SUMMARY OF THE INVENTION 
An object of this invention is to improve heat transfer and storage 
systems. 
Another object of this invention is to improve the operating 
characteristics of heat pumps. 
A further object of this invention is to reduce the size, cost, and 
complexity of a heat transfer and storage system. 
A still further object of this invention is to provide an improved heat 
pump and heat storage system which allows for the transfer of heat between 
the outdoors and an indoor enclosure between the indoor enclosure and a 
heat storage facility, and directly between the outdoors and the heat 
storage facility. 
A further object of this invention is to utilize in a heat transfer and 
storage system an integrated three medium heat exchanger which allows for 
the selective transfer of heat between two independent heat exchanging 
mediums as well as between each of these mediums and the ambient air. 
These and other objects are achieved by using in a heat transfer and 
storage system a three medium heat exchanger which has two independent 
fluid circuits each in thermal contact with the other as well as in 
thermal contact with the ambient air. A heat transfer medium such as water 
from a heat storage facility such as an insulated water tank can flow 
through one fluid circuit while another heat transfer medium such as a 
refrigerant from a heat pump can flow through the other circuit. A fan is 
provided which can force ambient air over the heat exchanger in thermal 
contact with the heat transfer mediums flowing through the heat exchanger. 
Heat can be exchanged between the two heat transfer mediums, and heat can 
be exchanged between any one or both of these mediums and the ambient air. 
In a preferred embodiment the three medium heat exchanger is located 
outside an enclosure in association with one coil of a heat pump, whose 
second coil is located inside the enclosure, and a water coil operatively 
connected to an insulated water tank. 
Further benefits and advantages of the invention will become apparent from 
a consideration of the following description given with reference to the 
accompanying drawings which specify and show a preferred embodiment of the 
invention.

A DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring to the drawings in detail, FIG. 1 is a mechanical schematic of a 
heat transfer and storage system constructed in accordance with the 
present invention. The system comprises, a heat pump 10 containing a heat 
transfer medium such as a refrigerant and a heat storage facility 50 such 
as an insulated water tank containing a heat exchanging medium such as 
water. While a preferred embodiment of the invention is used in 
combination with a solar heat collector 60, other types of heat sources 
can be combined with the heat transfer and storage system, or the heat 
transfer and storage system can be used alone to obtain the benefits, 
objectives, and advantages disclosed herein. 
The heat pump 10 comprises a compressor 12, a refrigerant flow reversing 
valve 14, a reversible expansion valve 16, an indoor coil 32 which is 
placed inside an enclosure 30, an outdoor coil 42, shown in FIGS. 2, 3, 
and 4, which is supported in a three medium heat exchanger 40, and 
refrigerant lines 22, 24, 26 and 28. A water pump 51 circulates water from 
the water tank 50 through a water supply line 52 to a water coil 44, shown 
in FIGS. 2, 3, and 4, which is supported in the three medium heat 
exchanger 40. The water circulates through the water coil 44 and then back 
to the water tank 50 through a water return line 54. Water return line 54 
carries the water through a solar heat collector 60. A by-pass valve 56 
and a by-pass water line 58 are provided to return the water from the 
water coil 44 directly to the water tank 50 when it is desired to by-pass 
the solar heat collector 60. Also, a fan 36 is provided to force ambient 
air over the indoor coil 32 of the heat pump 10, and a fan 46 is provided 
to force ambient air over both coils 42 and 44 of the heat exchanger 30. 
The three medium heat exchanger 40 is an air-water-refrigerant heat 
exchanger and, as shown in FIGS. 2, 3, and 4, is formed by 
interpositioning the outdoor coil 42 of the heat pump 10 with the water 
coil 44. The outdoor coil 42 is supported by and passed between tube 
sheets 48 and the refrigerant from the heat pump 10 is circulated through 
the coil 42 in either direction, as indicated by the dashed lines of FIGS. 
2, 3, and 4. The direction of flow of refrigerant depends upon the 
particular mode of operation of the heat pump 10. When the heat pump 10 is 
operating in its heating mode, that is, it is being used to heat the 
enclosure 30, the refrigerant circulates through coil 42 as shown by the 
dashed line in FIG. 3. When the heat pump 10 is operating in its cooling 
mode, that is, it is being used to cool the enclosure 30, the refrigerant 
circulates through coil 42 as shown by the dashed line in FIG. 4. The 
water coil 44 is also passed between the same tube sheets 48 and water 
from the storage tank 50 is circulated through the coil 44 in the 
direction indicated by the solid lines of FIGS. 2, 3, and 4. The coils 42 
and 44 are each supported by the tube sheets 48 in alternate, vertical 
planes and carry a plurality of common coil fins 49 throughout the length 
of the coil extending between the tube sheets 48. 
At the air-water-refrigerant heat exchanger 40 heat can be exchanged 
between the various heat transfer mediums passing through it. For example, 
by activating the heat pump 10 and water pump 51 and leaving the fan 46 
inactivated, heat can be exchanged between the heat pump refrigerant 
passing through coil 42 and the water passing through coil 44. Or by 
activating the heat pump 10 and the fan 46 and leaving the water pump 51 
inactivated, heat can be exchanged between the heat pump refrigerant 
passing through coil 42 and the ambient air. Or by activating water pump 
51 and the fan 46 and leaving the heat pump 10 inactivated, heat can be 
exchanged between the water passing through coil 44 and the ambient air. 
Heat can be put into the water tank 50, to be stored for later use, in a 
variety of ways. For example, if water pump 51 is activated, then water 
from the water tank 50 can pass through and absorb heat from the solar 
heat collector 60 and return to the water tank 50. Also, when the heat 
pump 10 is functioning in its cooling mode, that is, it is being used to 
cool the enclosure 30 and waste heat from the enclosure 30 is being 
transferred by the heat pump 10 from the indoor coil 32 to the outdoor 
coil 42, this waste heat can be transferred to the water tank 50 by 
activating the water pump 51. Water pump 51 circulates water from the 
water tank 50 through the water coil 44. While passing through the water 
coil 44, the water can absorb heat from the refrigerant passing through 
the outdoor coil 42. This heated water then returns to the water tank 50 
either directly or through the solar heat collector 60. In this manner, 
waste heat from the enclosure 30 can be taken out of the enclosure 30 and 
stored in the heat storage facility 50 for later use. 
To better illustrate the manner in which the heat transfer and storage 
system of the present invention functions, the system will be described 
for both heating and cooling the enclosure 30. 
To heat the enclosure 30, fans 36 and 46 are activated and the heat pump 10 
is activated in its heating mode. At the outdoor coil 42 the heat pump 
refrigerant absorbs heat from the ambient air as this air is forced over 
the outdoor coil 42 by the fan 46. The heat pump 10 then transfers this 
heat to the indoor coil 32 where it is released to the ambient air being 
forced over the coil 32 by fan 36. 
If the heat pump 10 cannot transfer enough heat from the outdoor air to the 
enclosure 30 to satisfactorily warm the enclosure 30, then heat that had 
previously been put into the water tank 50 can be used to assist the heat 
pump 10. This assistance is initiated by activating water pump 51. Water 
pump 51 circulates water from the water tank 50 through the water coil 44 
of the heat exchanger 40. The water carries heat that had been stored in 
the water tank 50. As the water passes through water coil 44 much of this 
heat is transferred to the refrigerant passing through the outdoor coil 42 
of the heat pump 10 which then transfers this heat, along with any heat 
absorbed from the ambient air, to the enclosure 30 via the indoor coil 32. 
If the enclosure 30 can be satisfactorily warmed by heat transferred to 
the enclosure via the heat pump 10 from the storage tank 50 alone so that 
it is not necessary to transfer any heat from the outdoor air to the 
enclosure, then the fan 46 can be deactivated and ambient air will not be 
forced over the outdoor coil 42. After leaving the water coil 44, the 
water can pass by means of water return line 54 through the solar heat 
collector 60 and then return to the water tank 50 so that radiant heat 
from the sun can be transferred to the water tank 50. Or, if it is desired 
to by-pass the solar heat collector 60, then water can pass from the water 
coil 44 to the water tank 50 through by-pass water line 58 by activating 
by-pass valve 56. 
To cool the enclosure, fans 36 and 46 are activated and the heat pump 10 is 
activated in its cooling mode. At the indoor coil 32 the heat pump 
refrigerant absorbs heat from the ambient air as this air is forced over 
the indoor coil 32 by fan 36. The heat pump 10 transfers this heat to the 
outdoor coil 42 where it is released to the ambient air being forced over 
the coil 42 by fan 46. Water pump 51 can be activated so that, as 
explained above, water from the water tank 50 passes through the water 
coil 44, absorbs heat from the refrigerant passing through the outdoor 
coil 42 of the heat pump 10, and then returns to the water tank 50. This 
is a useful mode of operation not only to store waste heat from the 
enclosure 30 for later use, but also, in case the water in the water tank 
50 is at a lower temperature than the air surrounding the outdoor coil 42, 
to improve the operating efficiency of the heat pump 10. 
While it is apparent that the invention herein disclosed is well calculated 
to fulfill the objects above stated, it will be appreciated that numerous 
modifications and embodiments may be devised by those skilled in the art 
and it is intended that the appended claims cover all such modifications 
and embodiments as fall within the true spirit and scope of the present 
invention.