US4940079A — Optimal control system for refrigeration-coupled …

Claim 1

Independent Claim 105 words

A method of controlling both the heating and cooling modes of a refrigeration-coupled thermal energy storage system, the control method comprising the steps of: selecting between the heating and cooling modes based upon outdoor temperature history; establishing target cooling and heating storage conditions based upon outdoor temperature history; operrating the system in the cooling mode, when selected, until the target cooling storage condition is achieved, such that cooling storage quantity increases with increases in outdoor temperature; and operating the system in the heating mode, when selected, until the target heating storage condition is achieved, such that heating storage quantity increases with decreases in outdoor temperature.

Claim 2

Independent Claim 105 words

A method of controlling both the heating and cooling modes of a refrigeration-coupled thermal energy storage system, the control method comprising the steps of: selecting between the heating and cooling modes based upon outdoor temperature history; establishing target cooling and heating storage conditions based upon outdoor temperature history; operrating the system in the cooling mode, when selected, until the target cooling storage condition is achieved, such that cooling storage quantity increases with increases in outdoor temperature; and operating the system in the heating mode, when selected, until the target heating storage condition is achieved, such that heating storage quantity increases with decreases in outdoor temperature.

Claim 3

Dependent Claim 103 words

The method of claim 1, further comprising the steps of: calculating a mode selection trigger value( T*) based upon outdoor temperature history; comparing the trigger value to first and second predetermined switch point temperatures (T c , T h ), the first switch point temperature being greater than the second; selecting the cooling mode of operation if the trigger value exceeds the first switch point temperature and it is determined to be the cooling season; and selecting the heating mode of operation if the trigger value is less than the second switch point temperature and it is determined to be the heating season.

Claim 4

Dependent Claim 90 words

The method of claim 2, further comprising the step of selecting neither the cooling mode nor the heating mode of operation if the trigger value is equal to either the first or second switch point temperature, if the trigger value is between the first and second switch point temperatures, if the trigger value exceeds the first switch point temperature but it is determined to be the heating season, or if the trigger value is less than the second switch point temperature but it is determined to be the cooling season.

Claim 5

Dependent Claim 25 words

The method of claim 2, wherein the trigger value is based upon average and maximum outdoor temperatures for the most recent period of predetermined duration.

Claim 6

Dependent Claim 60 words

The method of claim 4, wherein the trigger value is calculated according to the formula: T*=K.sub.1 T84 avg. 24 +K.sub.2 T.sub.84 max. 24 where T* is the trigger value, T 84 avg. 24 and T 84 max. 24 are the most recent 24 hour average and maximum outdoor temperatures, respectively, and K 1 and K 2 are gain adjustment/conversion factors.

Claim 7

Dependent Claim 143 words

The method of claim 1, wherein the cooling mode is controlled in accordance with the following steps: determining whether current time is within an on-peak period or an off-peak period in accordance with a current utility schedule; establishing an off-peak target storage ice fraction (NEWTAR) based upon outdoor temperature history, current storage temperature and current storage ice fraction; determining a necessary off-peak cooling cycle time (ESTHR) for achieving the off-peak target storage ice fraction; and determining a necessary off-peak cooling cycle starting time (STARTHR) for achieving the off-peak target storage ice fraction during the coolest portion of the off-peak period and by a predetermined off-peak time; and operating the system in the cooling mode if current time is at or after the off-peak cooling cycle starting time and if the current storage ice fraction is less than the off-peak target storage ice fraction.

Claim 8

Dependent Claim 18 words

The method of claim 6, wherein system operation in the cooling mode is prevented during the on-peak period.

Claim 9

Dependent Claim 55 words

The method of claim 6, wherein the value of the off-peak target storage ice fraction is increased with decreases in current storage ice fraction or increases in current storage temperature, and the value of the off-peak target storage ice fraction is decreased with increases in current storage ice fraction or decreases in current storage temperature.

Claim 10

Dependent Claim 31 words

The method of claim 6, wherein the value of the off-peak target storage ice fraction is based upon average and maximum outdoor temperatures for the most recent period of predetermined duration.

Claim 11

Dependent Claim 51 words

The method of claim 9, wherein the value of the off-peak target storage ice fraction is increased if either said average or said maximum outdoor temperature has increased, and the value of the off-peak target storage ice fraction is decreased if either said average or said maximum outdoor temperature has decreased.

Claim 12

Dependent Claim 111 words

The method of claim 9, wherein the value of the off-peak target storage ice fraction is calculated according to the formula: NEWTAR=K.sub.1 (% ICE.sub.81)+K.sub.2 (T.sub.84 max. 24 -T.sub.REF1) +K.sub.3 (T.sub.84 avg. 24 -T.sub.REF2)+K.sub.4 (T.sub.82 -T.sub.REF3) where NEWTAR is the off-peak target storage ice fraction, % ICE 81 is the current storage ice fraction, T 84 max 24 and T 84 avg. 24 are the most recent 24 hour maximum and average outdoor temperatures, respectively, T 82 is the current storage temperature, T REF1 through T REF3 are reference values for 24 hour maximum and average outdoor temperatures and storage temperature, respectively, and K 1 through K 4 are gain adjustment/conversion factors.

Claim 13

Dependent Claim 83 words

The method of claim 11, wherein the off-peak cooling cycle time and the off-peak cooling cycle starting time are calculated according to the formulas: (1) ESTHR=K 5 (NEWTAR-%ICE 81 )+K 6 ( T82 -T REF4 ), where ESTHR is the off-peak cooling cycle time, T REF4 is a reference value for storage temperature, and K 5 and K 6 are gain adjustment/conversion factors; (2) STARTHR=30-ESTHR, where STARTHR is the offpeak cooling cycle starting time; and (3) STARTHR=(30-ESTHR)-24, where 30-ESTHR is greater than 24.

Claim 14

Dependent Claim 69 words

The method of claim 6, further comprising the steps of: establishing an off-peak target storage temperature (SENTAR); and operating the system in the cooling mode during the off-peak period if the current storage temperature exceeds the off-peak target storage temperature even if current time is before the off-peak cooling cycle starting time or current storage ice fraction is greater than or equal to the off-peak target storage ice fraction.

Claim 15

Dependent Claim 35 words

The method of claim 6, further comprising the steps of: detecting an initial presence of storage ice with a storage temperature sensor; and detecting the storage ice fraction with a storage ice/water depth measuring device.

Claim 16

Dependent Claim 74 words

The method of claim 1, wherein the heating mode is controlled in accordance with the following steps: determining whether current time is within an on-peak period or an off-peak period in accordance with a current utility schedule; establishing an off-peak target storage temperature (HEATAR 2) based upon outdoor temperature history; and operating the system in the heating mode during the off-peak period if current storage temperature is less than the off-peak target storage temperature.

Claim 17

Dependent Claim 18 words

The method of claim 15, wherein system operation in the heating mode is prevented during the on-peak period.

Claim 18

Dependent Claim 28 words

The method of claim 15, wherein the value of the off-peak target storage temperature is based upon average outdoor temperature for the most recent period of predetermined duration.

Claim 19

Dependent Claim 35 words

The method of claim 17, wherein the off-peak target storage temperature is increased if said average outdoor temperature has decreased, and the off-peak target storage temperature is decreased if said average outdoor temperature has increased.

Claim 20

Dependent Claim 64 words

The method of claim 15, further comprising the steps of: establishing a hysteresis component at a value which is based upon outdoor temperature history and current time; and commencing operation of the system in the heating mode during the off-peak period when current storage temperature is less than the off-peak target storage temperature by an amount equal to said value of said hysteresis component.

Claim 21

Dependent Claim 192 words

The method of claim 15, further comprising the steps of: determining whether a most recent 24 hour minimum outdoor temperature is less than a reference value, and whether current time is between midnight and a predetermined morning time; establishing a hysteresis component at a first value if the most recent 24 hour minimum outdoor temperature is less than said reference value and current time is between midnight and said predetermined morning time, and commencing operation of the system in the heating mode during the off-peak period when current storage temperature is less than the off-peak target storage temperature by an amount equal to said first value of said hysteresis component; and establishing said hysteresis component at a second value, which is larger than said first value, if the most recent 24 hour minimum outdoor temperature is not less than said reference value or current time is not between midnight and said predetermined morning time, and commencing operation of the system in the heating mode during the off-peak period when current storage temperature is less than the off-peak target storage temperature by an amount equal to said second value of said hysteresis component.

Claim 22

Dependent Claim 47 words

The method of claim 15, further comprising the steps of: establishing an on-peak target storage temperature (HEATAR 1) based upon current outdoor temperature; and operating the system in the heating mode during the on-peak period if current storage temperature is less than the on-peak target storage temperature.

Claim 23

Dependent Claim 29 words

The method of claim 21, wherein the on-peak target storage temperature increases as current outdoor temperature decreases, and the on-peak target storage temperature decreases as current outdoor temperature increases.

Claim 24

Dependent Claim 154 words

The method of claim 21, wherein the on-peak and off-peak target storage temperatures are calculated according to the formulas: (1) HEATAR 1=T REF5 K 8 (T 84 -T REF6 ); (2) HEATAR 2=T SMA (if T 84 avg. 24 <T AR ); and (3) HEATAR 2=T SMA -M (T 84 avg. 24 -T AR ), but not less than T SMI (if T 84 avg. 24 ≧T AR ) where HEATAR 1 and HEATAR 2 are respectively the on-peak and off-peak target storage temperatures, T 84 is the current outdoor temperature, T 84 avg. 24 is the most recent 24 hour average outdoor temperature, T REF5 and T REF6 are reference values for on-peak target storage temperature and outdoor temperature, respectively, T SMA and T SMI are maximum and minimum off-peak target storage temperatures, respectively, T AR is a reference value for 24 hour average outdoor temperature, and M is a gain adjustment/conversion factor.

Claim 25

Dependent Claim 44 words

The method of claim 1, further comprising the steps of: detecting the level of storage liquid with a depth measuring device; and activating an automatic storage tank refill valve when the depth measuring device determines storage liquid depth to be below a predetermined level.

Claim 26

Dependent Claim 57 words

The method of claim 1, further comprising the step of preventing delivery of storage liquid to a building heat exchanger when outdoor temperature is below a first predetermined value and storage liquid temperature is below a second predetermined value, or when outdoor temperature exceeds a third predetermined value and storage liquid temperature exceeds a fourth predetermined value.

Claim 27

Dependent Claim 95 words

The method of claim 1, further comprising the steps of: determining whether current time is within an on-peak period or an off-peak period in accordance with a current utility schedule; operating the system during the on-peak period to produce domestic hot water if current domestic hot water tank temperature is less than a first predetermined value( DHWTAR 1); and operating the system during the off-peak period to produce domestic hot water if current domestic hot water tank temperature is less than a second predetermined value (DHWTAR 2), the second value being greater than the first.

Claim 28

Dependent Claim 17 words

The method of claim 26, wherein domestic hot water production is given priority over space conditioning functions.

Claim 29

Dependent Claim 47 words

The method of claim 26, further comprising the steps of operating the system to produce domestic hot water without operation of an outdoor heat exchanger fan when current domestic hot water tank temperature is greater than a third predetermined value which decreases continuously as outdoor temperature increases.

Claim 30

Dependent Claim 47 words

The method of claim 28, wherein one value is utilized as said third predetermined value when current storage temperature is greater than or equal to current outdoor temperature, and another value is utilized as said third predetermined value when current storage temperature is below current outdoor temperature.

Claim 31

Dependent Claim 33 words

The method of-claim 1, comprising the further step of activating a compressor crankcase heater when current compressor temperature is lower than one of current storage temperature and current outdoor heat exchanger coil temperature.

Claim 32

Dependent Claim 58 words

The method of claim 1, further comprising the steps of: defrosting an outdoor heat exchanger coil during said heating mode of operation in accordance with a first defrost mode when current outdoor temperature exceeds a predetermined value, and in accordance with a second defrost mode when current outdoor temperature is equal to or less than said predetermined value.

Claim 33

Dependent Claim 65 words

The method of claim 31, further comprising the steps of: defrosting in said first defrost mode by deactivating a compressor while operating an outdoor heat exchanger fan and a system cooling valve to permit hot refrigerant to flow into the outdoor heat exchanger coil; and defrosting in said second defrost mode by operating the system in cooling mode with the outdoor heat exchanger fan deactivated.

Claim 34

Dependent Claim 125 words

A control apparatus for a refrigeration-coupled thermal energy storage system, the control apparatus comprising: sensors for measuring outdoor and storage temperatures; a calendar and clock; means for storing the outdoor and storage temperatures; means for selecting between heating and cooling modes based upon outdoor temperature history; means for establishing target cooling and heating storage conditions based upon outdoor temperature history; and means for controlling the system so as to operate in the cooling mode, when selected, until the target cooling storage condition is achieved, such that cooling storage quantity increases with increases in outdoor temperature, and so as to operate in the heating mode, when selected, until the target heating storage condition is achieved, such that heating storage quantity increases with decreases in outdoor temperature.

Claim 35

Dependent Claim 125 words

A control apparatus for a refrigeration-coupled thermal energy storage system, the control apparatus comprising: sensors for measuring outdoor and storage temperatures; a calendar and clock; means for storing the outdoor and storage temperatures; means for selecting between heating and cooling modes based upon outdoor temperature history; means for establishing target cooling and heating storage conditions based upon outdoor temperature history; and means for controlling the system so as to operate in the cooling mode, when selected, until the target cooling storage condition is achieved, such that cooling storage quantity increases with increases in outdoor temperature, and so as to operate in the heating mode, when selected, until the target heating storage condition is achieved, such that heating storage quantity increases with decreases in outdoor temperature.

Claim 36

Dependent Claim 103 words

The control apparatus of claim 33, wherein said selecting means calculates a mode selection trigger value (T*) based upon outdoor temperature history, compares the trigger value to first and second predetermined switch point temperatures (T c , T h ), the first switch point temperature being greater than the second, selects the cooling mode of operation if the trigger value exceeds the first switch point temperature and it is determined to be the cooling season, and selects the heating mode of operation if the trigger value is less than the second switch point temperature and it is determined to be the heating season.

Claim 37

Dependent Claim 90 words

The control apparatus of claim 34, wherein said selecting means selects neither the cooling mode nor the heating mode of operation if the trigger value is equal to either the first or second switch point temperature, if the trigger value is between the first and second switch point temperatures, if the trigger value exceeds the first switch point temperature but it is determined to be the heating season, or if the trigger value is less than the second switch point temperature but it is determined to be the cooling season.

Claim 38

Dependent Claim 29 words

The control apparatus of claim 34, wherein said selecting means calculates the trigger value based upon average and maximum outdoor temperatures for the most recent period of predetermined duration.

Claim 39

Dependent Claim 63 words

The control apparatus of claim 36, wherein said selecting means calculates the trigger value according to the formula: T*=K.sub.1 T.sub.84 avg. 24 +K.sub.2 T.sub.84 max. 24 where T* is the trigger value, T 84 avg. 24 and T 84 max. 24 are the most recent 24 hour average and maximum outdoor temperatures, respectively, and K 1 and K 2 are gain adjustment/conversion factors.

Claim 40

Dependent Claim 161 words

The control apparatus of claim 33, further comprising means for determining whether current time is within an on-peak period or an off-peak period in accordance with a current utility schedule, wherein: said current utility schedule is stored within said storing means; said establishing means establishes, in said cooling mode, an off-peak target storage ice fraction (NEWTAR) based upon outdoor temperature history, current storage temperature and current storage ice fraction; determines a necessary off-peak cooling cycle time (ESTHR) for achieving the off-peak target storage ice fraction; and determines a necessary off-peak cooling cycle starting time (STARTHR) for achieving the off-peak target storage ice fraction during the coolest portion of the off-peak period and by a predetermined off-peak time; and said controlling means controls the system so as to operate in the cooling mode if current time is at or after the off-peak cooling cycle starting time and if the current storage ice fraction is less than the off-peak target storage ice fraction.

Claim 41

Dependent Claim 23 words

The control apparatus of claim 38, wherein said controlling means prevents operation of the system in the cooling mode during the on-peak period.

Claim 42

Dependent Claim 57 words

The control apparatus of claim 38, wherein said establishing means increases the value of the off-peak target storage ice fraction with decreases in current storage ice fraction or increases in current storage temperature, and decreases the value of the off-peak target storage ice fraction with increases in current storage ice fraction or decreases in current storage temperature.

Claim 43

Dependent Claim 32 words

The control apparatus of claim 38, wherein said establishing means establishes the off-peak target storage ice fraction based upon average and maximum outdoor temperatures for the most recent period of predetermined duration.

Claim 44

Dependent Claim 53 words

The control apparatus of claim 41, wherein said establishing means increases the value of the off-peak target storage ice fraction if either said average or said maximum outdoor temperature has increased, and decreases the value of the off-peak target storage ice fraction if either said average or said maximum outdoor temperature has decreased.

Claim 45

Dependent Claim 115 words

The control apparatus of claim 41, wherein said establishing means calculates the value of the off-peak target storage ice fraction in accordance with the formula: NEWTAR=K.sub.1 (% ICE.sub.81)+K.sub.2 (T.sub.84 max. 24 -T.sub.REF1) +K.sub.3 (T.sub.84 avg. 24 -T.sub.REF2)+K.sub.4 (T.sub.82 -T.sub.REF3) where NEWTAR is the off-peak target storage ice fraction, % ICE 81 is the current storage ice fraction, T 84 max. 24 and T 84 avg. 24 are the most recent 24 hour maximum and average outdoor temperatures, respectively, T 82 is the current storage temperature, T REF1 through T REF3 are reference values for 24 hour maximum and average outdoor temperatures and storage temperature, respectively, and K 1 through K 4 are gain adjustment/conversion factors.

Claim 46

Dependent Claim 86 words

The control apparatus of claim 43, wherein said establishing means calculates the off-peak cooling cycle time and the off-peak cooling cycle starting time according to the formulas: (1) ESTHR=K 5 (NEWTAR-%ICE 81 )+K 6 (T 82 -T REF4 ), where ESTHR is the off-peak cooling cycle time, T REF4 is a reference value for storage temperature, and K 5 and K 6 are gain adjustment/conversion factors; (2) STARTHR=30-ESTHR, where STARTHR is the off-peak cooling cycle starting time; and (3) STARTHR=(30-ESTHR)-24, where 30-ESTHR is greater than 24.

Claim 47

Dependent Claim 81 words

The control apparatus of claim 38, wherein: said establishing means further establishes, in said cooling mode, off-peak target storage temperature (SENTAR); and said controlling means controls the system so as to operate in the cooling mode during the off-peak period if the current target storage temperature exceeds the off-peak target storage temperature even if current time is before the off-peak cooling cycle starting time or current storage ice fraction is greater than or equal to the off-peak target storage ice fraction.

Claim 48

Dependent Claim 33 words

The control apparatus of claim 38, further comprising: a storage temperature sensor for detecting an initial presence of storage ice; and a storage ice/water depth measuring device for detecting the storage ice fraction.

Claim 49

Dependent Claim 92 words

The control apparatus of claim 33, further comprising means for determining whether current time is within an on-peak period or an off-peak period in accordance with a current utility schedule, wherein: said current utility schedule is stored in said storing means; said establishing means establishes, in said heating mode, an off-peak target storage temperature (HEATAR 2) based upon outdoor temperature history; and said controlling means controls the system so as to operate in the heating mode during the off-peak period if current storage temperature is less than the off-peak target storage temperature.

Claim 50

Dependent Claim 23 words

The control apparatus of claim 47, wherein said controlling means prevents operation of the system in the heating mode during the on-peak period.

Claim 51

Dependent Claim 32 words

The control apparatus of claim 47, wherein said establishing means establishes the value of the off-peak target storage temperature based upon average outdoor temperature for the most recent period of predetermined duration.

Claim 52

Dependent Claim 43 words

The control apparatus of claim 49, wherein said establishing means increases the value of the off-peak target storage temperature if said average outdoor temperature has decreased, and decreases the value of the off-peak target storage temperature if said average outdoor temperature has increased.

Claim 53

Dependent Claim 75 words

The control apparatus of claim 47, wherein: said establishing means further establishes, in said heating mode, a hysteresis component at a value which is based upon outdoor temperature history and current time; and said controlling means controls the system so as to commence operation in the heating mode during the off-peak period when current storage temperature is less than the off-peak target storage temperature by an amount equal to said value of said hysteresis component.

Claim 54

Dependent Claim 221 words

The control apparatus of claim 47, further comprising means for determining whether a most recent 24 hour minimum outdoor temperature is less than a reference value, and whether current time is between midnight and a predetermined morning time, wherein: said establishing means further establishes, in said heating mode, a hysteresis component at a first value if the most recent 24 hour minimum outdoor temperature is less than said reference value and current time is between midnight and said predetermined morning time, and said controlling means controls the system so as to commence operation in the heating mode during the off-peak period when current storage temperature is less than the off-peak target storage temperature by an amount equal to said first value of said hysteresis component; and said establishing means further establishes, in said heating mode, said hysteresis component at a second value, which is larger than said first value, if the most recent 24 hour minimum outdoor temperature is not less than said reference value or current time is not between midnight and said predetermined morning time, and said controlling means controls the system so as to commence operation in the heating mode during the off-peak period when current storage temperature is less than the off-peak target storage temperature by an amount equal to said second value of said hysteresis component.

Claim 55

Dependent Claim 59 words

The control apparatus of claim 47, wherein: said establishing means further establishes, in said heating mode, an on-peak target storage temperature (HEATAR 1) based upon current outdoor temperature; and said controlling means controls the system so as to operate in the heating mode during the on-peak period if current storage temperature is less than the on-peak target storage temperature.

Claim 56

Dependent Claim 39 words

The control apparatus of claim 5, wherein said establishing means increases the value of the on-peak target storage temperature as current outdoor temperature decreases, and decreases the value of the on-peak target storage temperature as current outdoor temperature increases.

Claim 57

Dependent Claim 160 words

The control apparatus of claim 5, wherein said establishing means calculates the values of the on-peak and off-peak target storage temperatures according to the formulas: (1) HEATAR 1=T REF5 -K 8 (T 84 -T REF6 ); (2) HEATAR 2=T SMA (if T 84 avg. 24 <T AR ); and (3) HEATER 2=T SMA -M (T 84 avg. 24 -T AR ), but not less than T SMI (if T 84 avg. 24 ≧T AR ) where HEATAR 1 and HEATAR 2 are respectively the on-peak and off-peak target storage temperatures, T 84 is the current outdoor temperature, T 84 avg. 24 is the most recent 24 hour average outdoor temperature, T REF5 and T REF6 are reference values for on-peak target storage temperature and outdoor temperature, respectively, T SMA and T SMI are maximum and minimum off-peak target storage temperatures, respectively, T AR is a reference value for 24 hour average outdoor temperature, and M is a gain adjustment/conversion factor.

Claim 58

Dependent Claim 45 words

The control apparatus of claim 33, further comprising a depth measuring device for detecting the level of storage liquid, wherein said controlling means activates an automatic storage tank refill valve when the depth measuring device determines storage liquid depth to be below a predetermined level.

Claim 59

Dependent Claim 57 words

The control apparatus of claim 56, said depth measuring device including: means for projecting an ultrasonic ray onto the surface of the storage liquid; means for sensing the ultrasonic ray after being reflected from the surface of the storage liquid; and means for generating an output voltage proportional to the total travel distance of the ultrasonic ray.

Claim 60

Dependent Claim 38 words

The control apparatus of claim 57, said depth measuring device further including horizontal and vertical tubes through which said ultrasonic ray is transmitted, and an angled reflection surface between the horizontal and vertical tubes for providing horizontal-to-vertical-to-horizontal transition.

Claim 61

Dependent Claim 63 words

The control apparatus of claim 33, further comprising a building heat exchanger, wherein said controlling means prevents delivery of storage liquid to the building heat exchanger when outdoor temperature is below a first predetermined value and storage liquid temperature is below a second predetermined value, or when outdoor temperature exceeds a third predetermined value and storage liquid temperature exceeds a fourth predetermined value.

Claim 62

Dependent Claim 115 words

The control apparatus of claim 33, further comprising means for determining whether current time is within an on-peak period or an off-peak period in accordance with a current utility schedule, wherein: said current utility schedule is stored in said storing means; and said controlling means controls the system so as to operate during the on-peak period to produce domestic hot water if current domestic hot water tank temperature is less than a first predetermined value (DHWTAR 1), and so as to operate during the off-peak period to produce domestic hot water if current domestic hot water tank temperature is less than a second predetermined value (DHWTAR 2), the second value being greater than the first.

Claim 63

Dependent Claim 21 words

The control apparatus of claim 60, wherein said controlling means gives priority to domestic hot water production over space conditioning functions.

Claim 64

Dependent Claim 63 words

The control apparatus of claim 60, further comprising an outdoor heat exchanger and an outdoor heat exchanger fan, wherein said controlling means controls the system so as to operate to produce domestic hot water without operation of the outdoor heat exchanger fan when current domestic hot water tank temperature is greater than a third predetermined value which decreases continuously as outdoor temperature increases.

Claim 65

Dependent Claim 49 words

The control apparatus of claim 62, wherein said controlling means utilizes one value as said third predetermined value when current storage temperature is greater than or equal to current outdoor temperature, and utilizes another value as said third predetermined value when current storage temperature is below current outdoor temperature.

Claim 66

Dependent Claim 58 words

The control apparatus of claim 33, further comprising a compressor, a compressor crankcase heater, an outdoor heat exchanger coil, and sensors for measuring compressor and outdoor heat exchanger coil temperatures, wherein said controlling means activates the compressor crankcase heater when current compressor temperature is lower than one of current storage temperature and current outdoor heat exchanger coil temperature.

Claim 67

Dependent Claim 71 words

The control apparatus of claim 33, further comprising an outdoor heat exchanger coil, wherein said controlling means controls the system so as to defrost the outdoor heat exchanger coil during the heating mode of operation in accordance with a first defrost mode when current outdoor temperature exceeds a predetermined value, and in accordance with a second defrost mode when current outdoor temperature is equal to or less than said predetermined value.

Claim 68

Dependent Claim 89 words

The control apparatus of claim 65, further comprising a compressor, an outdoor heat exchanger fan, and a system cooling valve, wherein said controlling means controls the system so as to defrost the outdoor heat exchanger coil in said first defrost mode by deactivating the compressor while operating the outdoor heat exchanger fan and the system cooling valve to permit hot refrigerant to flow into the outdoor heat exchanger coil, and in the second defrost mode by operating the system in cooling mode with the outdoor heat exchanger fan deactivated.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1993-07-09	1994-01-08	1994-07-10	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1997-07-09	1998-01-08	1998-07-10	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2001-07-09	2002-01-08	2002-07-10	$7700.00	Window Closed / Lapsed

Optimal control system for refrigeration-coupled thermal energy storage

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