|Publication number||US2797068 A|
|Publication date||Jun 25, 1957|
|Filing date||Dec 21, 1953|
|Priority date||Dec 21, 1953|
|Publication number||US 2797068 A, US 2797068A, US-A-2797068, US2797068 A, US2797068A|
|Inventors||Alden I Mcfarlan|
|Original Assignee||Alden I Mcfarlan|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (7), Referenced by (59), Classifications (13)|
|External Links: USPTO, USPTO Assignment, Espacenet|
A. l. M FARLAN AIR CONDITIONING SYSTEM June 25, 1957 2 Sheets-Sheet 1 Filed Dec. 21, 1953 INVENTOR filden I McFa I'Zcuz fi ATT June 25, 1957 A. l. McFARLAN 2,797,068
AIR CONDITIONING SYSTEM Filed Dec. 21, 1953 2 Sheets Sheet 2 INVENTOR .2148, j. McFaz-Zazn n J I ATTOR N United States Patent Am CONDETIONTNG SYSTEM Alden ll. McFarlan, Westfield, N. J. Application December 21, 1953, Serial No. 399,507 14 Claims. (Cl. 25'73) This invention relates to air conditioning, and more particularly to air conditioning systems wherein heating and cooling operations are accomplished; with a seasonal changeover from one to the others, and with it being possible to provide simultaneously, cooling of one zone of the conditioned space and heating of another zone of the space.
An object of this invention is to provide air conditioning systems which are efiicient through wide ranges of application and use. A further object is to provide such systems wherein the different zones of an air conditioned space may be selectively heated or cooled with a single system. A further object is to provide systems of the above character wherein automatic controls are provided to insure eflicient and dependable operation at all times. Another object is to provide systems wherein heat is removed from and supplied to the various zones of the conditioned space and the excess heat may be dissipated from the system by a cooling tower, all in an efiicient and dependable manner. Another object is to provide systems wherein heat removed from one space is used to heat another space which may require heat while the first space requires cooling, and wherein any excess heat is dissipated to a cooling tower or any deficiency of heat is supplied from an outside source. These and other objects will be in part obvious and in part pointed out below.
In the drawings:
Figure 1 is a somewhat schematic representation of one embodiment of the invention in the form of an air conditioning system for a multi-zone building; and
Figure 2 is a somewhat simplified similar view of another embodiment of the invention.
Referring to Figure 1 of the drawings, a building is represented as having a conditioned space divided into three zones 2, 4 and 6 which are individually heated and cooled respectively by coils 8, 10 and 12 each having a fan or blower 14 directing air over it. These coils are components of a heating and cooling system which also includes: a first-stage refrigeration system 16; a secondstage refrigeration system 18; a third-stage refrigeration system 19; a water-spray cooling tower 20; and, a waterheating unit or converter 22. Each of coils 8, 10 and 12 is connected at one side to a water discharge line 24 which extends to the condenser 25 of the third-stage refrigeration system 19 which also has a compressor 27, an evaporator 29, refrigerant lines, and an expansion valve 31 through which liquid refrigerant flows from the condenser to the evaporator. The water from condenser 25 passes through a line 33 to condenser 26 of the secondstage refrigeration system 18 which also has: a compressor 28, an evaporator 30, an expansion valve 32, and refrigerant lines. The water flows from condenser 26 through a line 34 to condenser 36 of the first-stage refrig eration system 16 which has a compressor 38, an evaporator 40, refrigerant lines, and an expansion valve 42. A water circulating pump 35 in line 34 causes the flow described. The water flows from condenser 36 through a line 43 which has one branch line 44 extending to the water-heating unit 22, and another line 46 extending upwardly to a water cooling coil 48 of the cooling tower 20. Line 46 is also connected through a line 50 to a vented expansion tank 52.
games Patented June 25, 1957 Cooling tower 20 has a casing 54 in the bottom of which there is a sump tank 56 which is kept filled with cooling Water. This cooling water is withdrawn from the sump tank by a pump 58, and the water is discharged through a spray header or other distributing device 60 in the top of the tower onto coil 48. A fan 62 at the top of the tower draws air into the sides of casing 54 through louvers 64 and discharges the air at the top. The sprayed water falls downwardly over coil 48 and thence over water-contact packing 66, counter-current to the upflowing stream of air. The sprayed water thence flows on downwardly over an after-cooling coil 68, and returns to the sump.
The after-cooling coil 68 is connected by a line 70 to coil 48, and at the outlet side to a final subcooling coil 69 which is connected at its outlet side by a line 72 to the water circuit of evaporator 48. The cooled water then flows from evaporator 40 through a line 74 to the Water circuit of evaporator 30 and thence through a line 73 to the water circuit of evaporator 29. The cold water flows from evaporator 29 through a line 76 back to the various coils 8, 10 and 12. The cold water flows from line 76 to these coils individually, respectively through the threeway valves 78, 80 and 82. These valves are also connected to a line 84 which extends from the heater unit 22 and carries the hot water which flows to unit 22 through line 44. Y
Valves 78, 80 and 82 are automatically-controlled throttling valves, and each acts in accordance with the temperature condition and demand in its space to supply its coil with the desired amount of hot or cold water. It should be noted that the showing of three coils 8, 10 and 12 is illustrative and the system would include the number of coils desirable for any particular installation. Hence, one or more coils may be supplied with hot water from line 84, while one or more other coils are being supplied with cold water from line 76, and the other coils are not receiving any water. Under some circumstances, each of valves 78, 80 and 82 may be replaced by a pair of independently operated throttling valves respectively connecting lines 76 and 84 to the coil. Under other circumstances, each of the coils is connected to the hot and cold lines through a three-way valve which has no throttling function, and a throttling valve is then inserted into the line. The throttling valve will have a temperature throttling control which operates to open the valve with rises in temperature when cooling is being carried on, but is reversed so as to close the valve with rises in temperature when heating is being carried on. The throttling control may be responsive to the temperature of the air leaving the coil.
Line 70, which carries water from coil 48 to coil 68 has a branch line 86 with a throttling valve 88 therein extending to line 34 between condensers 26 and 36. Thus, some of the partially cooled water from coil 48 is bled off under the control of valve 88 and added to the water flowing from condenser 26. Valve 88 is normally closed, but is gradually opened when the refrigerant pressure in condenser 36 rises to an abnormally high value. As is fully discussed below, in this way the temperature of the water supplied to condenser 36 is reduced wherever the refrigerant pressure rises above a predetermined set pressure.
It has been indicated above that the water level in sump tank 56 is maintained at a predetermined level. This is accomplished by supplying feed water through a ice float-controlled valve 90 to a spray head 92 above the' sub-cooling coil 69. Thus, the water which is evaporated as a result of the spraying operation is replaced by feed water which is sprayed over coil 69 and then falls into the sump tank 56. As will be discussed more fully below, the feed water normally has a lower temperature than the water being sprayed and this feature is utilized to obtain a sub-cooling of the water in coil 69.
The above-described closed water circuit will now be discussed. From coils 8, and 12 the water flows in succession through the Water circuits of condensers 25, 26 and 36 where the water is heated; some water is then bled off through line 44v to heater unit 22 where it is further heated if necessary to provide the desired temperature of hot water in line 84. The main stream of water from condenser 36 flows through coil 48 where it is cooled by heat transfer with the sprayed water, some of which is being evaporated, and with the air. The water then flows through coil 68 where it is further cooled by the spray water dropping down from packing 66. The water is then further cooled in coil 69 by the fresh water from spray head 92.
Under marginal conditions of operation where only a small amount of cooling is required, the water spray may be dispensed with and suflicient cooling is obtained by the contact of the air with the cooling coils 48, 68 and 69. This avoids difficulties which are encountered where the water being circulated through the system is cooled by spraying it in a cooling tower, and the spray must be shut off and the tower drained when temperatures fall to the vicinity of freezing and the system isrendered inoperative. With such a prior system, the operator may decide to drain the tower in the early fall because of an extremely cold night and he must then turn the water on again at any time that warmer weather requires that the system be placed in operation. With the system of the present invention, the tower spray system may be drained as before, but the lighter loads which are encountered thereafter may be handled without the use of spray water.
Ashas been indicated above, some of the water from coil 48 may be diverted through line 86 to line 34 so that some of the cooled water is added to the stream of water passing to condenser 36. This flow of water through line 86 is controlled by valve.88- which opens only when the refrigerant head pressure of compressor 38 rises above a pre-determined volume. This insures proper operation of the first-stage refrigeration system 16. However, at all times, the main water stream flows from coil 48' and thence through evaporators 40, and 29 to line 76, which acts as the source of cold water to coils 8, 10and 12.
The amount of steam supplied to unit 22 is controlled by a valve 94.having:a sensing bulb 91 on line 84 to maintain a predetermined hot water temperature in line 84'.
However, valve. 94 is held closed whenever the outside:
temperature sensed by bulb 93 is above a predetermined value, or when. water from. the condensers is sufficiently warm to satisfy all heating loads. In this way the heating is by reverse cycle. operation except when the outside temperature drops. Valve 94 also has-a bypass line 95 which is. manually opened during warm-up periods to heat the space and which is closed by a timer after a warm-up? period has elapsed.
For maximum efliciency during reverse cycle operations, it is desirable to discontinue the flow of water '(the circulating fluid) through the coils of the cooling tower so as to prevent dissipation and. heatfrom the system. Accordingly, the system" is arranged so that water is supplied from theheat transfer coils 8, 10-or 12 directly to the evaporator circuit, i; e.,tothe first-stage evaporator 16. For this purpose a bypass line 97' having a pump 99 and a check valve 100 therein is connected from line 24 to line 72. The pump may be. operated to pump water from line 24 to line 72 and the check valve permits free flow in:that direction but prevents reverse flow. Line 46 has a check valve 102 which permits upward flow as dis cussed above. but'whiclr prevents reverse flow through the coils ofthe cooling tower when pump 99 is operating.
For reverse cycle operation, pump 99 is started and pump'35 continues to operate as discussed above. Pump 99-maintains a pressure head through the water cooling as with tower 20 in Figure 1.
the outside air in the cooling tower;
circuit of the evaporators and maintains a constant supply of cooling water in line 76. Pump 35 continues to maintain a pressure head in line 44 so that heated water is available in line 84 and auxiliary heating may be provided as discussed above. However, the cooling which is effected is beneficial to the reverse cycle heating operation and the reverse cycle heating operation benefits the cooling operation.
In the above discussion the term water has been applied to the liquid or fluid which is circulated through the closed circuit. However, in the present embodiment this is a water and glycol alcohol or other nonfreezing solution which will not freeze at temperatures which are apt to be encountered, i. e., at the lowest outside temperature. Thus the coils of the cooling tower are not drained during the cold months but the closed system operates the year round without-being drained and with only the changes in the modes of operation as discussed. During weather when freezing temperatures are apt to be encountered, the spray system is drained and the water supply thereto is turned off. However, this is a relatively simple operation and draining does not involve the loss of a substantial amount of water. The system may be used etficiently at all times utilizing the outside air with or without the spray to produce cooling. The system is then readily converted to operate as a heat pump or to operate with reverse cycle heating and conventional cooling andthere may be auxiliary heating. The system may alsobe operated as a pure heating system by stopping the. refrigeration systems and relyingsolely upon this steam as. asource of heat. However, even when operated in that manner, cooling water is available because the coils: of the coolingtower are still connected into the circuit and the required amount of water is cooled to maintain asource of cold water in line 76.
The system has-the additional advantage that the water which is circulated is, not contaminated by exposure to Hence, it is unnecessary to drain and clean the system as would be necessary with certain other types of systems.
Referring now to Figure 2 wherein another embodiment of the invention is shown, the system is identical with that of Figure 1 except as shown in the drawings and aspointed out below. In Figure 2, there are four cooling towers, 104, 106, 108 and 110'. These towers are provided with water spray and air-flow equipment thesame However, in Figure 2, each of the towers has only a single coil 112 and these coils are connected in series so that water fromline 46 flows through the four coils in series to line 72. This arrangement permits cooling of the water in successive stages so that its'temperature is brought down to a low value.
This application is related to my co-pending application Serial No. 238,430 filed July 25, 1951, now abandoned. In that application, as well as in the systems of the present application, the air cooling coils are of substantial depth so that the air cooling fluid circulating through the coils has its temperature raised in the order of 20 to 40 F. At the same time, the air passing through each coil has its temperature lowered substantiallythe same amount as the rise in temperature of the air cooling fluid.
1. In an air conditioning system, the combination of, a plurality of refrigeration systems each of which contains a refrigerant and has an evaporator and condenser, each evaporator and condenser having a passage for a heat transfer fluid, a plurality of heat transfer units having passages for said heat transfer fluid and which are adapted to have air pass therethrough in heat exchange relationship with said heat transfer fluid, a cooling tower including water sprayer means and means to pass air into heat transfer relationship with water spray from said sprayer means thereby to evaporate water and cool the water and air, said tower also including conduit means for heat transfer fluid through which said heat transfer fluid flows thereby to cool said fluid as a result of the flow of air and the water spray in the tower, and fluid conduit means interconnecting the heat transfer fluid passages of the said condensers in series to form a fluid heating circuit having a branch through said condensers and heat transfer units thereby to provide a supply of heated fluid which is available for passage through said heat transfer units and a branch through which the fluid flows through said fluid conduit means of said cooling tower if not directed through said heat transfer units, said latter branch having fluid conduit means also providing a cooling circuit for said heat transfer fluid through said cooling tower, evaporators in series and thence to said heat transfer units thereby to provide a source of cooling fluid which is available for passage through said heat transfer units, and conduit means connected between said heat transfer units and said branches to complete the heating and cooling circuits.
2. In an air conditioning system, the combination of, refrigeration apparatus which subjects a stream of fluid to successive cooling actions thereby to provide a stream of cold fluid and which subjects a stream of fluid to successive heating actions thereby to produce a stream of heated fluid, a cooling tower having conduit means therein which receives all or part of said stream of heated fluid and cools the fluid and thereafter supplies the fluid to be cooled by said refrigeration apparatus, a plurality of heat transfer units connected to receive fluid from the cold stream and hot stream and which pass air in heat transfer relationship with said fluid passing therethrough, and fluid control means to supply each of said heat transfer units with fluid selectively from said stream of cooled fluid for a cooling operation or from said stream of heated fluid for a heating operation.
3. In an air conditioning system as described in claim 2 wherein said refrigeration apparatus is in the form of a plurality of refrigeration systems each of which has a fluid cooling evaporator and a fluid heating condenser, and which includes pump means directing fluid through the condensers to perform the heating operation.
4. A system as described in claim 2 which includes, auxiliary heating means to perform an auxiliary heating operation upon the stream of heated fluid passing to said heat transfer units.
5. A system as described in claim 2 wherein said refrigeration apparatus is in the form of a plurality of independently operating refrigerating systems each of which has a fluid heating condenser and a fluid cooling evaporator and which are connected in series whereby the heating and cooling operations are carried on in successive stages, pump means to direct the fluid through the last of said condensers in the series, diverting means to divert water from said cooling back to the fluid stream flowing to said last condenser, and control means to control said diverting means in response to an excessive rise in refrigerant pressure flowing to said last condenser.
6. A system as described in claim 5 which includes, auxiliary heating means, heat control means to control the supply of heat to said auxiliary heating means in response to a drop in temperature of the heated fluid being supplied to said heat transfer units, said heat control means including means responsive to a rise in the outside temperature above a predetermined value to prevent the supplying of heat to said auxiliary heating means.
7. A system as described in claim 5 wherein said cooling tower includes, first, second, and third cooling coils forming said conduit means, water spray means which is adapted to spray water onto first said cooling coil and which water is thereafter cooled by counter-current flow with air which produces evaporation of water and which water then flows over said second cooling coil, and feed water supply means to said cooling tower which sprays the feed water onto said third cooling coil.
8. A system as described in claim 7 which includes, means to by-pass a portion of the fluid from said heat transfer units to the first of said evaporators.
9. A system as described in claim 2 which includes a cooling tower construction comprising a plurality of coils positioned in separate cooling tower spaces and connected in series whereby fluid is subjected to a progressive cooling action when flowing through the coils.
10. In an air conditioning system, the combination of, refrigeration apparatus which produces a cooling eflect upon one stream of liquid to produce a stream of cold liquid by a plurality of cooling stages and which produces a heating effect upon another stream of liquid to produce a stream of heated liquid by a plurality of heating stages, an air coil assembly which receives cold liquid from said stream and cools air with the liquid having its temperature raised in the order of 20 to 40 F. and with the air being cooled a corresponding amount, and a cooling tower system having a closed fluid circuit therein which receives said stream of heated liquid and subjects it to an air and Water spray cooling operation and delivers the liquid thus cooled to be further cooled by said refrigeration system, thus to provide said stream of cold liquid.
11. A system as described in claim 10 wherein said cooling tower system comprises a plurality of cooling tower units, each of which includes a coil through which said stream of heated liquid flows and spray means to spray water thereon.
12. In an air conditioning system, the combination of, refrigeration apparatus in the form of a plurality of individually operating refrigeration systems each of which includes a condenser and an evaporator, air cooling coil means through which air flows to be cooled, pumps and fluid line means to pass a stream of liquid into heat exchange relationship with said evaporatorsin series and thence through said coil means, a plurality of cooling tower units having liquid cooling coils which are connected in series, and circuit means to direct a stream of liquid into heat exchange relationship with said condensers in series and thence through said liquid cooling coils.
13. A system as described in claim 12 wherein said circuit means is a closed circuit and the liquid cooling coils therein are cooled by the combined action of water spray and air.
14. In an air conditioning system, the combination of, refrigeration apparatus which comprises a plurality of refrigeration systems each of which includes an evaporator and a condenser and which produces a cooling effect upon one stream of a liquid flowing through said evaporator to provide a stream of cold liquid and which produces a heating effect upon another stream of liquid flowing through said condensers to provide a stream of heated liquid, means to pass one of said streams of liquid through said evaporators in series and the other of said streams through said condensers in series, a deep cooling coil which receives cold liquid from said stream and cools air, said cooling coil being so constructed and arranged as to cool the air through a range of the order of 20 to 40 F. and with the liquid having its temperature raised a substantially similar amount, said coil being connected to receive heated liquid from said stream and heating air passing through the coils, and a cooling tower system which receives said stream of heated liquid and subjects it to an air cooling operation.
References Cited in the file of this patent UNITED STATES PATENTS 1,980,688 Lewis Nov. 13, 1934 2,152,250 Gay Mar. 28, 1939 2,292,335 Durbin Aug. 4, 1942 2,304,243 Crawford Dec. 8, 1942 2,463,881 Kemler Mar. 8, 1949 2,715,514 Stair Aug. 16, 1955 2,715,515 Stair Aug. 16, 1955
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US1980688 *||May 29, 1930||Nov 13, 1934||Lewis Air Conditioners Inc||Air conditioning and refrigeration system|
|US2152250 *||Sep 3, 1935||Mar 28, 1939||Gay Norman H||Continuous cycle heating and cooling system|
|US2292335 *||Aug 27, 1941||Aug 4, 1942||Stephen A Durbin||Air conditioning apparatus|
|US2304243 *||Mar 3, 1939||Dec 8, 1942||Crawford Robert B P||Air conditioning system|
|US2463881 *||Jul 6, 1946||Mar 8, 1949||Muncie Gear Works Inc||Heat pump|
|US2715514 *||Sep 10, 1951||Aug 16, 1955||York Corp||Air conditioning system|
|US2715515 *||Sep 10, 1951||Aug 16, 1955||York Corp||Air conditioning system|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US2883836 *||Jun 28, 1956||Apr 28, 1959||Sacks Bernard||System for utilizing heat removed from a refrigerated space|
|US2928260 *||Feb 8, 1957||Mar 15, 1960||Borg Warner||Air conditioning systems|
|US2966047 *||Feb 7, 1958||Dec 27, 1960||Normalair Ltd||Cooling of cabins and other compartments|
|US2971460 *||Mar 30, 1959||Feb 14, 1961||Shindle George H||Method and apparatus for automatic temperature control of rotary printing press ink rollers|
|US3024008 *||Jan 23, 1958||Mar 6, 1962||Borg Warner||Three-pipe air conditioning systems|
|US3069867 *||May 29, 1961||Dec 25, 1962||Trane Co||Summer-winter air conditioning system|
|US3165148 *||Jul 19, 1961||Jan 12, 1965||American Radiatory & Standard||Air conditioning system|
|US3171471 *||Feb 27, 1962||Mar 2, 1965||Borg Warner||Multi-room air conditioning systems|
|US3180109 *||Aug 21, 1963||Apr 27, 1965||Emhart Corp||System for operating refrigerated equipment|
|US3186183 *||Nov 20, 1964||Jun 1, 1965||John P Murdoch||Air conditioning system|
|US3191667 *||Dec 29, 1960||Jun 29, 1965||Trane Co||Air conditioning system and pump controls therefor|
|US3191668 *||Dec 29, 1960||Jun 29, 1965||Trane Co||Pump control system|
|US3210957 *||Aug 18, 1964||Oct 12, 1965||Emhart Corp||System for refrigerating display cases|
|US3214100 *||Dec 26, 1961||Oct 26, 1965||Worthington Corp||Loading and drive systems for heat pumps|
|US3259317 *||Aug 13, 1965||Jul 5, 1966||Worthington Corp||Loading and drive systems for heat pumps|
|US3276516 *||Apr 26, 1965||Oct 4, 1966||Worthington Corp||Air conditioning system|
|US3305001 *||Oct 26, 1964||Feb 21, 1967||Itt||Plural zone heating and cooling system|
|US3318371 *||Jul 1, 1963||May 9, 1967||Borg Warner||Air conditioning systems|
|US3320762 *||Dec 8, 1965||May 23, 1967||Murdoch John P||Air conditioning system with heating means|
|US3354943 *||Mar 11, 1965||Nov 28, 1967||Alden I Mcfarlan||Air conditioning system|
|US3378062 *||Oct 27, 1966||Apr 16, 1968||Trane Co||Four pipe heat pump apparatus|
|US3404728 *||Apr 8, 1966||Oct 8, 1968||Singer Co||Air conditioning system|
|US3490517 *||May 20, 1968||Jan 20, 1970||Nat Service Ind Inc||Dynamically integrated comfort conditioning system|
|US3496992 *||May 25, 1961||Feb 24, 1970||Carrier Corp||Method and apparatus for heating and cooling|
|US3523575 *||Jun 12, 1968||Aug 11, 1970||American Standard Inc||Air-conditioning system having heat storage reservoir|
|US3527060 *||Aug 26, 1968||Sep 8, 1970||Whirlpool Co||Heat pump for selectively heating or cooling a space|
|US3850007 *||Jan 24, 1974||Nov 26, 1974||Mcfarlan A||Air conditioning system and method|
|US4010624 *||Nov 25, 1974||Mar 8, 1977||Mcfarlan Alden I||Air conditioning system|
|US4143523 *||Oct 25, 1977||Mar 13, 1979||Burger Manfred R||Apparatus to transfer heat or refrigerant|
|US4263785 *||Aug 6, 1979||Apr 28, 1981||Barniak Richard L||Method and system for recovering heat in association with dairy operations|
|US4265094 *||Oct 4, 1979||May 5, 1981||Haasis Jr Hans||Unitized refrigeration and water heating system|
|US4419864 *||Sep 14, 1981||Dec 13, 1983||Mcfarlan Alden I||Air conditioning system and method|
|US4457358 *||Aug 8, 1983||Jul 3, 1984||Engineering Design And Management Inc.||Heating and cooling system|
|US4510762 *||Mar 26, 1984||Apr 16, 1985||H. Krantz Gmbh & Co.||Heat recovery method|
|US4559788 *||Sep 26, 1983||Dec 24, 1985||Mcfarlan Alden I||Air conditioning system and method|
|US5044172 *||Oct 30, 1987||Sep 3, 1991||Takenaka Corporation||Air conditioning apparatus|
|US6959556 *||Aug 12, 2003||Nov 1, 2005||Sanyo Electric Co., Ltd.||Stirling refrigeration system|
|US6993918 *||Feb 12, 2004||Feb 7, 2006||Advanced Thermal Sciences||Thermal control systems for process tools requiring operation over wide temperature ranges|
|US7065979 *||Oct 29, 2003||Jun 27, 2006||Delaware Capital Formation, Inc.||Refrigeration system|
|US7152426||Dec 21, 2005||Dec 26, 2006||Advanced Thermal Sciences||Thermal control systems for process tools requiring operation over wide temperature ranges|
|US7337625||Nov 1, 2006||Mar 4, 2008||Advanced Thermal Sciences||Thermal control systems for process tools requiring operation over wide temperature ranges|
|US8141623 *||Mar 27, 2012||Blecker Joseph G||Automatic switching two pipe hydronic system|
|US8397799 *||Mar 27, 2012||Mar 19, 2013||Joseph G. Blecker||Automatic switching two pipe hydronic system|
|US8631666||Aug 7, 2008||Jan 21, 2014||Hill Phoenix, Inc.||Modular CO2 refrigeration system|
|US9303904 *||Oct 28, 2009||Apr 5, 2016||Mitsubishi Electric Corporation||Air-conditioning apparatus|
|US9310087 *||Sep 29, 2010||Apr 12, 2016||Carrier Corporation||System and method for maintaining air temperature within a building HVAC system|
|US9335074 *||Oct 28, 2009||May 10, 2016||Mitsubishi Electric Corporation||Air-conditioning apparatus|
|US9353958 *||Feb 10, 2010||May 31, 2016||Mitsubishi Electric Corporation||Air-conditioning apparatus|
|US20040025519 *||Aug 12, 2003||Feb 12, 2004||Takashi Inoue||Stirling refrigeration system|
|US20040148956 *||Oct 29, 2003||Aug 5, 2004||Delaware Capital Formation, Inc.||Refrigeration system|
|US20080271881 *||May 1, 2007||Nov 6, 2008||Blecker Joseph G||Automatic Switching Two Pipe Hydronic System|
|US20100031697 *||Aug 7, 2008||Feb 11, 2010||Dover Systems, Inc.||Modular co2 refrigeration system|
|US20110146317 *||Jun 23, 2011||Trane International Inc.||Bi-directional cascade heat pump system|
|US20120118005 *||Sep 10, 2009||May 17, 2012||Mitsubishi Elrctric Corporation||Air-conditioning apparatus|
|US20120181009 *||Jul 19, 2012||Blecker Joseph G||Automatic Switching Two Pipe Hydronic System|
|US20120198872 *||Oct 28, 2009||Aug 9, 2012||Mitsubishi Electric Corporation||Air-conditioning apparatus|
|US20120204585 *||Oct 28, 2009||Aug 16, 2012||Mitsubishi Electric Corporation||Air-conditioning apparatus|
|US20120245739 *||Sep 29, 2010||Sep 27, 2012||Carrier Corporation||System and method for maintaining air temperature within a building hvac system|
|US20120304675 *||Feb 10, 2010||Dec 6, 2012||Mitsubishi Electric Corporation||Air-conditioning apparatus|
|U.S. Classification||165/207, 62/305, 62/435, 62/159, 165/220, 62/335, 165/50, 165/240, 165/63|
|Cooperative Classification||F25B2400/06, F24F3/10|