CA2298754A1 - Cooling system with variable capacity condenser - Google Patents
Cooling system with variable capacity condenser Download PDFInfo
- Publication number
- CA2298754A1 CA2298754A1 CA 2298754 CA2298754A CA2298754A1 CA 2298754 A1 CA2298754 A1 CA 2298754A1 CA 2298754 CA2298754 CA 2298754 CA 2298754 A CA2298754 A CA 2298754A CA 2298754 A1 CA2298754 A1 CA 2298754A1
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- Prior art keywords
- condenser
- coil
- refrigerant
- cooling system
- coil sections
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
- F25B49/027—Condenser control arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B6/00—Compression machines, plants or systems, with several condenser circuits
- F25B6/02—Compression machines, plants or systems, with several condenser circuits arranged in parallel
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/19—Pressures
- F25B2700/195—Pressures of the condenser
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
- F25B2700/2106—Temperatures of fresh outdoor air
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Devices That Are Associated With Refrigeration Equipment (AREA)
Abstract
Refrigerant closed loop cooling system condenser that is variable in volume during operation by having a plurality of parallel refrigerant flow though paths and solenoid operated valves in the paths for switching circuits in and out of the refrigerant flow path as required during operation and a cooling system having such a condenser, Each parallel flow through path has a one way flow control valve permitting refrigerant flow only from the inlet side of the condenser to the outlet side. The cooling system condenser is controlled by a central processing unit or programmed logic controller in response to signals from a refrigerant pressure sensor upstream of the condenser, a refrigerant pressure sensor downstream of the condenser and an ambient air temperature sensor and further sensors if warranted by the particular system at hand.
Description
Title VariablEa capacity Condenser Coil and Cooling System Incorporating The Same Field of Invention This invention relates to cooling systems of medium to large size with condenser coils located outdoors where the ambient temperature varies and more particularly to a cooling system that automatically compensates for pressure loss/gain in response to temperature change by controllably varying the condenser coil capacity.
Background of Invention In cooling ;systems with an outdoor condenser coil, as the ambient temperature drops, there is pressure loss in the condenser coil and liquid lines. However certain pressures must be maintained in the condenser coil and liquid lines to ensure the cooling system works properly. The colder the ambient air the greater the pressure a>0 loss .
One traditi~~nal method of controlling this refrigerant ;pre.osure has been to turn on and off the condenser fa.n motor, or modulate its speed, to reduce air flow though the coil and thereby artificially raising the refrigerant pressure.
There has been limited success using this method in some installations. Most condenser coils of medium and large size are horizontal and have a very large area of finned tubing. Because the coil is warm it creates a chimney effect and draws air across the coil even when the fans are turned off in cold weather. This causes the coil to drop refrigerant pressure and it begins logging refrigerant in the coil creating a back flooding condition. This uses a large amount of refrigerant which is relatively costly. Also as much as 90$ of the coil can fill with liquid refrigerant and should a leak develop it becomes not only exp~ensi.ve to refill but also the loss of refrigerant is environmentally unfriendly.
Some other method of controlling pressure must be used when two or more cooling systems are ~'.0 circuited in the: same condenser coil as is often done in commercial systems. It is next to impossible t~~ cycle fans in this instance because of the plura:Lity of systems and thus it is impossible to control the pressures evenly.
Another instance where fan cycling is next to impossible is where heat reclaim coils are used to make use of t:he heat rejected by cooling systems and use that reclaimed heat to heat a building or heat. water etc. In most instances these reclaim heat exchangers are connected in series with the condenser coils and often cause the condenser coils to partially fill with liquid l0 refrigerant. Controlled back flooding is used in the installations where controlled air flow is not a satisfactory solution. A back flooding valve controls the refrigerant pressure and flow by controlling t:he back flooding of the condenser coils sometimes to the extent of 97$ being liquid refrigerant. A back flooding valve works well, it is very durable and trouble free. It provides good refrigerant: pressure control and there is no need to cycle the condenser fans. A back flooding ;?0 valve however is required on each and every cooling system individually circuited inside a common condenser coil.
A problem with the two forgoing methods of pressure contro:L is the enormous amount of refrigerant required. It is referred to as a winter refrigerant charge and a summer refrigerant charge, the former normally being three or more times the latter. A fully charged system will have 1000 pounds or more of refrigerant and costs in the range of $20 to $60 per pound.
Refrigerants are expensive and since leaks in a system are not: uncommon replacement of lost refrigerant can,, in the medium to large cooling systems, be a major expense. Proposals to reduce the quantity of refrigerant in a system have included reducing the tube size in the outdoor l5 condenser coil and still use a back flooding valve. While this partially reduces the charge it is not particularly effective since it causes an increase in the pressure drop across the coil.
The acceptable normal pressure drop is 10 PSI
;?0 while a reduced tube size can result in a pressure drop of up to 30 PSI.
Another method of reducing the quantity of refrigerant, commonly used in supermarket cooling systems, is to monitor the liquid line and in response thereto control a set of solenoid valves, that under certain conditions, will isolate the recs~iver from the cooling system for certain periods of time. During cooling cycles, where the system charge becomes critical, the controller has t:o continuously re-adjust the refrigerant charge .
In the forgoing the cooling system closed l0 loop refrigerani~ piping has a constant volume and the refrigerant pressure in the condenser is controllably varied by using liquid refrigerant to vary the effective condensing area of the coil.
l5 Summary of Invention A principle object of the present invention is to provide a cooling system in which the winter refrigerant charge is equal in quantity to the present summer charge.
;?0 A furthE~r principal object of the present invention is to provide a condenser coil and means to controllably vary the volume of the tubing thereof i.n response to condenser pressure requirements In substance the present invention involves controlling the refrigerant flow through the condenser coil by in affect adding tubing to or removing tubing from the refrigerant flow path.
In accordan~~e with the present invention a programmed central processing unit(CPU), responsive to ambient temperature and refrigerant pressures, variEas the tubing volume as required l0 to maintain a predetermined condenser pressure for the sensed ambient temperature and refrigerant pre:>sures. The tubing volume is adjusted by 'what: is referred to herein as 'coil splitting'. The term 'coil splitting' refers to a l5 coil subdivided into a plurality of parallel coil sections and having valves to vary the number of sections that are in parallel. Valve means, responsive to the CPU, is used to control refrigerant flov~r to the condenser coil sections ~!0 ie the number of sections as may be required in the particular circumstances. This coil splitting controls the condenser size to meet requirements for the system. The CPU processes information received from an ambient air temperature sensor, a first pressure sensor that detects the refrigerant pressure on the exhaust side of the compressor, ie upstream of the condenser and a second pressure sensor, downstream of the condenser, that detects the liquid refrigerant pressure. Pressure transducers are preferably used. The CPU determines what to do and how many coil sections are required and self adjusts as the system operates. The colder the weather the lesser the number of coil sections required and the warmer it gets the more coil sections required. In some systems there are two further sensors one relating to the mechanical room and l5 that is to t~=11 the CPU how many compressors are operating in the refrigerant loop and the other is when there are heat recovery coils in which case a sensor provides signals from the diverter valve.
~',0 The present cooling system with its components a:nd C:PU provides good control of refrigerant :pressure and system operation in all seasons and 'temperatures while using only a normal summer refrigerant charge. This means the refrigerant charge is only 1/3 that of existing cooling systems and thus a tremendous saving not only in the initial charge but also replacement of the refrigerant should a leak occur. There is no cycling of the condenser fans and there are no back flooding valves.
Li s t of Drawi nQ:~
The invention is illustrated by way of example in the accompanying drawing wherein:
Figure ~l diagrammatically illustrates a cooling system of the present invention in its simplest form; and Figure 2 is similar to figure 1 but including additional components.
Description of Preferred Embodiment Referring to figure 1 there is illustrated, in its simplest form, a cooling system comprising a compressor 10, a condenser coil 20, an ~?0 evaporator coil 30 and an expansion valve 40 connected by refrigerant piping in a closed loop.
The refrigerant piping includes a first pipe A connected ;at one end to the exhaust side of the compressor 10 and at the other end to the intake side of the condenser coil 20, a second pipe B
connected at onEa end to the output side of the condenser coil 20 and at the other end to the expansion valve 40, a third pipe C connected at one end to the expansion valve 40 and at the other end to the evaporator coil 30 and a fourth pipe D connected at one end to the evaporator coil 30 and .at the other end to the intake side of the compressor 10. A sight glass CG is in the pipe B as well a.s a line filter FR.
The condenser coil has a plurality of coil sections ds~signated respectively 20A, 20B, 20C, 20D, 20E, fOF, 20G, 20H, and 20I which are l5 connected in parallel. The coil sections 20B to 20I inclusive are selectively connected in and out of the refrigerant circuit by respective solenoid operated valves 21B, 21C, 21D, Z1E, 21F, 21G, 21H and 21I. These valves are actuated by :>.0 signals from a suitably programmed central processing unit (or a programmed logic controller) CP in response to signals from a liquid refrigerant first pressure sensor (or transducer) 50, a second gaseous refrigerant pressure sen.sor(or transducer) 60 and an ambient air temperature sensor 70. In systems having more than one compressor a further sensor will tell 5 the CPU how many compressors are in operation and in systems having heat recovery coils a further sensor provides signals from the diverter valve to the CPU.
Each coi:L section, at its outlet end, has a 10 one way flow control valve that prevents back flow into the condenser. The coil sections 20A to 20I inclusive have respective flow control valves 22A to 22I inclusive .
The cool~.ng system of figure 2 is the same as that in figure 1 but optionally includes a receiver 80 and an evaporator pressure regulator valve 90 Also there is one or more compressors l0A connected ira parallel with the compressor 10 (there may b~e as many as required for the system ~~0 at hand) and the tubing of the condenser is in a series-parallel relation.
Various types of sensors can be used for example pressure switches, pressure transducers, thermostats, thermocouples, diodes and thermistors. They central processing unit can be variously programmed to accomplish the results required for the system at hand and, by way of example, it may be a micro programmed logic controller (PLC) available from G.E. Fanuc Automation sold under the TM ~~Series 90".
The sequence in which the valves are opened and closed is such as to ensure that refrigerant logged in the various circuits is pushed or flushed out. It is preferred that the last valve to close on 'the last cycle is the first to open on the next ~:ycle. Generally the valves will be opened in the reverse order in which they previously clossad.
In large commercial and industrial cooling systems there normally are two or more compressors connected to one condenser coil and at some time all will be required to be in ~?0 operation. However if only one compressor is operating then only a portion of the coil is required. The central processing unit can readily be programmed for that situation.
The condenser coil 20 can be variously positioned, for example vertical or horizontal, and the tubing c:an be variously constructed. Also all of the coil sections may be in parallel or alternatively in a series-parallel relation.
Figure 1 is illustrative of all coil sections being in parallel relation while figure 2 represents the coil sections as being in a parallel-series relation.
l0 Referring further to figure 2 there are four coil sections designated respectively 101, 102, 103 and 104. and these sections are connected in parallel. Each section has a zig-zag arrangement of tubing in series. There are solenoid operated valves, at t:he inlet end, permitting bringing the coil sections into or out of the refrigerant circuit by respectively opening and closing the valve associated therewith. The solenoid operated valves are designated 105, 106, 107 and 108 for a!0 respective coil sections 101,102,103, and 104 and further one way flow control valves 109,110,111 and 112, at i~he outlet side, prevent back flow into the res~~ect.ive coil sections .
One coil section of coils 20 and 100 can be an open circuit without a solenoid valve because anytime the sy~:tem is running, or has to run, it will always need at least one flow path to circulate the refrigerant regardless of the outdoor ambient temperature(note coil section 20A
in figure 1 does not have an inflow control valve). As the pressure increases more valves are opened to use more coil. As pressure drops the valves are closed(in the reverse sequence) and an appropriate number closed to maintain the requisite pressure. By way of example the compressor exhaust pressure will be maintained at about 100 psi when medium pressure refrigerants ~5 as are used ouch as FR12, 134or 414 and about 170 to 180 PSI wizen medium pressure refrigerants are used such as R22, 408 or 502. There are of course many other refrigerants and the foregoing are only by way of example.
~'.0 Referring further to figure 2 there is a receiver tank 80~ in the refrigerant pipe 8. In some installations there will be such a tank but as previouslyy mentioned the control of the present system is such that a receiving tank normally is not necessary. There is about a 10$
saving in energy when the system does not have a receiver and thus should not be used unless really needed. In this figure the control unit CP
has respective leads L1 and L2 for receiving signals from sensors associated respectively with a diverter valve: and the number of compressors in operation in sy.~tems where applicable.
l0 In each of f.-'igures 1 and 2 the sensors are illustrated as being hard wired to the CPU but obviously wireless operation is feasible.
During operation the sensors provide information to t:he suitably programmed controller l5 CP. The information includes how many compressors are operating, urhat is the outdoor temperature and the refrigerant pressures at the intake and outlet sides of the condenser relative to the target pressure:.. A selected number of the coil ~'.0 sections are in circuit and if the two pressures meet the target pressure ie a 'yes' condition no changes are made. On the other hand should the sensed conditions not meet the preselected conditions ie a 'no' situation then more, or less circuits, are switched in, or out, as the case may be. If the gas pressure is too high then more coil sections ie more circuits are switched in 5 until the preselected conditions are met. Should the pressure be too low coil circuits are cut out until the preselected conditions are met. If the pressure conditions are still not met (ie pressure too low) the controller switches into IO search mode in which coil sections are al ternately swi 1=ched in and out of ci rcui t to flush out logged refrigerant or the number of coil circuits are reduced and then starts alternating circuits to flush out the refrigerant 15 putting it back into the system. After being flushed out coil. sections will then be switched in, or out a;s the case may be, until the desired preselected conditions are reached.
If there is a heat reclaim coil in series ?0 with the out doer condenser, and if the 'yes' situation is applicable, then one or two circuits in the roof ~~ond.enser are turned on to act as a pipe. On the other hand if it is a series-parallel system then there is no need to turn on circuits in the roof condenser.
There is a power driven condenser cooling fan 130 suitably located to drive air across the coil tubing of the parallel coil sections.
l0 l5 a? 0
Background of Invention In cooling ;systems with an outdoor condenser coil, as the ambient temperature drops, there is pressure loss in the condenser coil and liquid lines. However certain pressures must be maintained in the condenser coil and liquid lines to ensure the cooling system works properly. The colder the ambient air the greater the pressure a>0 loss .
One traditi~~nal method of controlling this refrigerant ;pre.osure has been to turn on and off the condenser fa.n motor, or modulate its speed, to reduce air flow though the coil and thereby artificially raising the refrigerant pressure.
There has been limited success using this method in some installations. Most condenser coils of medium and large size are horizontal and have a very large area of finned tubing. Because the coil is warm it creates a chimney effect and draws air across the coil even when the fans are turned off in cold weather. This causes the coil to drop refrigerant pressure and it begins logging refrigerant in the coil creating a back flooding condition. This uses a large amount of refrigerant which is relatively costly. Also as much as 90$ of the coil can fill with liquid refrigerant and should a leak develop it becomes not only exp~ensi.ve to refill but also the loss of refrigerant is environmentally unfriendly.
Some other method of controlling pressure must be used when two or more cooling systems are ~'.0 circuited in the: same condenser coil as is often done in commercial systems. It is next to impossible t~~ cycle fans in this instance because of the plura:Lity of systems and thus it is impossible to control the pressures evenly.
Another instance where fan cycling is next to impossible is where heat reclaim coils are used to make use of t:he heat rejected by cooling systems and use that reclaimed heat to heat a building or heat. water etc. In most instances these reclaim heat exchangers are connected in series with the condenser coils and often cause the condenser coils to partially fill with liquid l0 refrigerant. Controlled back flooding is used in the installations where controlled air flow is not a satisfactory solution. A back flooding valve controls the refrigerant pressure and flow by controlling t:he back flooding of the condenser coils sometimes to the extent of 97$ being liquid refrigerant. A back flooding valve works well, it is very durable and trouble free. It provides good refrigerant: pressure control and there is no need to cycle the condenser fans. A back flooding ;?0 valve however is required on each and every cooling system individually circuited inside a common condenser coil.
A problem with the two forgoing methods of pressure contro:L is the enormous amount of refrigerant required. It is referred to as a winter refrigerant charge and a summer refrigerant charge, the former normally being three or more times the latter. A fully charged system will have 1000 pounds or more of refrigerant and costs in the range of $20 to $60 per pound.
Refrigerants are expensive and since leaks in a system are not: uncommon replacement of lost refrigerant can,, in the medium to large cooling systems, be a major expense. Proposals to reduce the quantity of refrigerant in a system have included reducing the tube size in the outdoor l5 condenser coil and still use a back flooding valve. While this partially reduces the charge it is not particularly effective since it causes an increase in the pressure drop across the coil.
The acceptable normal pressure drop is 10 PSI
;?0 while a reduced tube size can result in a pressure drop of up to 30 PSI.
Another method of reducing the quantity of refrigerant, commonly used in supermarket cooling systems, is to monitor the liquid line and in response thereto control a set of solenoid valves, that under certain conditions, will isolate the recs~iver from the cooling system for certain periods of time. During cooling cycles, where the system charge becomes critical, the controller has t:o continuously re-adjust the refrigerant charge .
In the forgoing the cooling system closed l0 loop refrigerani~ piping has a constant volume and the refrigerant pressure in the condenser is controllably varied by using liquid refrigerant to vary the effective condensing area of the coil.
l5 Summary of Invention A principle object of the present invention is to provide a cooling system in which the winter refrigerant charge is equal in quantity to the present summer charge.
;?0 A furthE~r principal object of the present invention is to provide a condenser coil and means to controllably vary the volume of the tubing thereof i.n response to condenser pressure requirements In substance the present invention involves controlling the refrigerant flow through the condenser coil by in affect adding tubing to or removing tubing from the refrigerant flow path.
In accordan~~e with the present invention a programmed central processing unit(CPU), responsive to ambient temperature and refrigerant pressures, variEas the tubing volume as required l0 to maintain a predetermined condenser pressure for the sensed ambient temperature and refrigerant pre:>sures. The tubing volume is adjusted by 'what: is referred to herein as 'coil splitting'. The term 'coil splitting' refers to a l5 coil subdivided into a plurality of parallel coil sections and having valves to vary the number of sections that are in parallel. Valve means, responsive to the CPU, is used to control refrigerant flov~r to the condenser coil sections ~!0 ie the number of sections as may be required in the particular circumstances. This coil splitting controls the condenser size to meet requirements for the system. The CPU processes information received from an ambient air temperature sensor, a first pressure sensor that detects the refrigerant pressure on the exhaust side of the compressor, ie upstream of the condenser and a second pressure sensor, downstream of the condenser, that detects the liquid refrigerant pressure. Pressure transducers are preferably used. The CPU determines what to do and how many coil sections are required and self adjusts as the system operates. The colder the weather the lesser the number of coil sections required and the warmer it gets the more coil sections required. In some systems there are two further sensors one relating to the mechanical room and l5 that is to t~=11 the CPU how many compressors are operating in the refrigerant loop and the other is when there are heat recovery coils in which case a sensor provides signals from the diverter valve.
~',0 The present cooling system with its components a:nd C:PU provides good control of refrigerant :pressure and system operation in all seasons and 'temperatures while using only a normal summer refrigerant charge. This means the refrigerant charge is only 1/3 that of existing cooling systems and thus a tremendous saving not only in the initial charge but also replacement of the refrigerant should a leak occur. There is no cycling of the condenser fans and there are no back flooding valves.
Li s t of Drawi nQ:~
The invention is illustrated by way of example in the accompanying drawing wherein:
Figure ~l diagrammatically illustrates a cooling system of the present invention in its simplest form; and Figure 2 is similar to figure 1 but including additional components.
Description of Preferred Embodiment Referring to figure 1 there is illustrated, in its simplest form, a cooling system comprising a compressor 10, a condenser coil 20, an ~?0 evaporator coil 30 and an expansion valve 40 connected by refrigerant piping in a closed loop.
The refrigerant piping includes a first pipe A connected ;at one end to the exhaust side of the compressor 10 and at the other end to the intake side of the condenser coil 20, a second pipe B
connected at onEa end to the output side of the condenser coil 20 and at the other end to the expansion valve 40, a third pipe C connected at one end to the expansion valve 40 and at the other end to the evaporator coil 30 and a fourth pipe D connected at one end to the evaporator coil 30 and .at the other end to the intake side of the compressor 10. A sight glass CG is in the pipe B as well a.s a line filter FR.
The condenser coil has a plurality of coil sections ds~signated respectively 20A, 20B, 20C, 20D, 20E, fOF, 20G, 20H, and 20I which are l5 connected in parallel. The coil sections 20B to 20I inclusive are selectively connected in and out of the refrigerant circuit by respective solenoid operated valves 21B, 21C, 21D, Z1E, 21F, 21G, 21H and 21I. These valves are actuated by :>.0 signals from a suitably programmed central processing unit (or a programmed logic controller) CP in response to signals from a liquid refrigerant first pressure sensor (or transducer) 50, a second gaseous refrigerant pressure sen.sor(or transducer) 60 and an ambient air temperature sensor 70. In systems having more than one compressor a further sensor will tell 5 the CPU how many compressors are in operation and in systems having heat recovery coils a further sensor provides signals from the diverter valve to the CPU.
Each coi:L section, at its outlet end, has a 10 one way flow control valve that prevents back flow into the condenser. The coil sections 20A to 20I inclusive have respective flow control valves 22A to 22I inclusive .
The cool~.ng system of figure 2 is the same as that in figure 1 but optionally includes a receiver 80 and an evaporator pressure regulator valve 90 Also there is one or more compressors l0A connected ira parallel with the compressor 10 (there may b~e as many as required for the system ~~0 at hand) and the tubing of the condenser is in a series-parallel relation.
Various types of sensors can be used for example pressure switches, pressure transducers, thermostats, thermocouples, diodes and thermistors. They central processing unit can be variously programmed to accomplish the results required for the system at hand and, by way of example, it may be a micro programmed logic controller (PLC) available from G.E. Fanuc Automation sold under the TM ~~Series 90".
The sequence in which the valves are opened and closed is such as to ensure that refrigerant logged in the various circuits is pushed or flushed out. It is preferred that the last valve to close on 'the last cycle is the first to open on the next ~:ycle. Generally the valves will be opened in the reverse order in which they previously clossad.
In large commercial and industrial cooling systems there normally are two or more compressors connected to one condenser coil and at some time all will be required to be in ~?0 operation. However if only one compressor is operating then only a portion of the coil is required. The central processing unit can readily be programmed for that situation.
The condenser coil 20 can be variously positioned, for example vertical or horizontal, and the tubing c:an be variously constructed. Also all of the coil sections may be in parallel or alternatively in a series-parallel relation.
Figure 1 is illustrative of all coil sections being in parallel relation while figure 2 represents the coil sections as being in a parallel-series relation.
l0 Referring further to figure 2 there are four coil sections designated respectively 101, 102, 103 and 104. and these sections are connected in parallel. Each section has a zig-zag arrangement of tubing in series. There are solenoid operated valves, at t:he inlet end, permitting bringing the coil sections into or out of the refrigerant circuit by respectively opening and closing the valve associated therewith. The solenoid operated valves are designated 105, 106, 107 and 108 for a!0 respective coil sections 101,102,103, and 104 and further one way flow control valves 109,110,111 and 112, at i~he outlet side, prevent back flow into the res~~ect.ive coil sections .
One coil section of coils 20 and 100 can be an open circuit without a solenoid valve because anytime the sy~:tem is running, or has to run, it will always need at least one flow path to circulate the refrigerant regardless of the outdoor ambient temperature(note coil section 20A
in figure 1 does not have an inflow control valve). As the pressure increases more valves are opened to use more coil. As pressure drops the valves are closed(in the reverse sequence) and an appropriate number closed to maintain the requisite pressure. By way of example the compressor exhaust pressure will be maintained at about 100 psi when medium pressure refrigerants ~5 as are used ouch as FR12, 134or 414 and about 170 to 180 PSI wizen medium pressure refrigerants are used such as R22, 408 or 502. There are of course many other refrigerants and the foregoing are only by way of example.
~'.0 Referring further to figure 2 there is a receiver tank 80~ in the refrigerant pipe 8. In some installations there will be such a tank but as previouslyy mentioned the control of the present system is such that a receiving tank normally is not necessary. There is about a 10$
saving in energy when the system does not have a receiver and thus should not be used unless really needed. In this figure the control unit CP
has respective leads L1 and L2 for receiving signals from sensors associated respectively with a diverter valve: and the number of compressors in operation in sy.~tems where applicable.
l0 In each of f.-'igures 1 and 2 the sensors are illustrated as being hard wired to the CPU but obviously wireless operation is feasible.
During operation the sensors provide information to t:he suitably programmed controller l5 CP. The information includes how many compressors are operating, urhat is the outdoor temperature and the refrigerant pressures at the intake and outlet sides of the condenser relative to the target pressure:.. A selected number of the coil ~'.0 sections are in circuit and if the two pressures meet the target pressure ie a 'yes' condition no changes are made. On the other hand should the sensed conditions not meet the preselected conditions ie a 'no' situation then more, or less circuits, are switched in, or out, as the case may be. If the gas pressure is too high then more coil sections ie more circuits are switched in 5 until the preselected conditions are met. Should the pressure be too low coil circuits are cut out until the preselected conditions are met. If the pressure conditions are still not met (ie pressure too low) the controller switches into IO search mode in which coil sections are al ternately swi 1=ched in and out of ci rcui t to flush out logged refrigerant or the number of coil circuits are reduced and then starts alternating circuits to flush out the refrigerant 15 putting it back into the system. After being flushed out coil. sections will then be switched in, or out a;s the case may be, until the desired preselected conditions are reached.
If there is a heat reclaim coil in series ?0 with the out doer condenser, and if the 'yes' situation is applicable, then one or two circuits in the roof ~~ond.enser are turned on to act as a pipe. On the other hand if it is a series-parallel system then there is no need to turn on circuits in the roof condenser.
There is a power driven condenser cooling fan 130 suitably located to drive air across the coil tubing of the parallel coil sections.
l0 l5 a? 0
Claims (11)
1. A condenser, for a refrigerant closed loop cooling system, comprising a coil sub-divided into a plurality of coil sections, means connecting said coil sections into parallel circuits, said coil sections each having an inlet end and an outlet end, solenoid actuated valves located in selected ones of said coil sections, said valves being located at the inlet end of the coil section associated therewith and one way flow control valves in each of said coil sections and located at the outlet side thereof preventing back flow into the respective sections.
2. A condenser as defined in claim 1 wherein each coil section has a valve at the inlet end thereof.
3. A condenser as defined in claim 1 in which it is a horizontal unit.
4. A condenser as defined in claim 1 in which it is a vertical unit.
5. A condenser as defined in claim 1 including a power driven condenser cooling fan located to circulate air across the coil sections.
6. A cooling system comprising a compressor, a condenser coil, an evaporator coil, an expansion valve and refrigerant piping means connecting said components in a closed loop refrigerant cooling system, said condenser coil comprising a plurality of coil sections, means connecting said coil sections in parallel, said coil sections having an inlet end and an outlet end with the inlet end thereof being connected to the exhaust side of said compressor, valve means in selected ones of said coil sections selectively controlling flow of refrigerant through the coil section associated therewith and one way flow control valve means in each of said coil sections and located at the outlet side thereof preventing back flow of refrigerant into the respective coil sections.
7. A cooling system as defined in claim 6 including refrigerant pressure sensing means providing output signals in response to refrigerant pressures at the inlet and outlet sides of said condenser, an ambient air temperature sensing means providing an output signal responsive to the sensed ambient temperature and signal processing means receiving said signals and in response thereto controlling actuation of said valves selectively to vary the number of coil sections in circuit in said closed loop as required by the system during operation.
8. A cooling system as defined in claim 7 wherein said valves at the inlet side of the condenser are solenoid actuated.
9. A cooling system as defined in claim 7 wherein said condenser is a horizontal unit.
10. A cooling system as defined in claim 7 wherein said coil sections have the tubing thereof in a zig-zag series-parallel relation.
11. A cooling system as defined in claim 7 including a receiver in said refrigerant piping at a location upstream of said evaporator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2298754 CA2298754A1 (en) | 2000-02-11 | 2000-02-11 | Cooling system with variable capacity condenser |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2298754 CA2298754A1 (en) | 2000-02-11 | 2000-02-11 | Cooling system with variable capacity condenser |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2298754A1 true CA2298754A1 (en) | 2001-08-11 |
Family
ID=4165326
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2298754 Abandoned CA2298754A1 (en) | 2000-02-11 | 2000-02-11 | Cooling system with variable capacity condenser |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2298754A1 (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1455149A1 (en) * | 2003-03-07 | 2004-09-08 | Linde Kältetechnik GmbH & Co.KG | A connection-ready refrigerator and arrangement of such a refrigerator |
| EP2091314A3 (en) * | 2008-02-13 | 2011-11-02 | Hitachi Plant Technologies, Ltd. | Cooling system for electronic equipment |
| CN102889706A (en) * | 2012-10-22 | 2013-01-23 | 合肥天鹅制冷科技有限公司 | Compression refrigeration condensation system with low-temperature startup and low-temperature operation |
| WO2013145006A1 (en) * | 2012-03-29 | 2013-10-03 | 三菱電機株式会社 | Air conditioning device |
| CN104501440A (en) * | 2015-01-14 | 2015-04-08 | 合肥天鹅制冷科技有限公司 | Cooling liquid forced air cooling regulation system |
| CN105783331A (en) * | 2016-05-10 | 2016-07-20 | 合肥天鹅制冷科技有限公司 | Heat efficient recovery device for air source water chilling unit |
| US11268739B2 (en) * | 2018-01-12 | 2022-03-08 | Schneider Electric It Corporation | System for head pressure control |
-
2000
- 2000-02-11 CA CA 2298754 patent/CA2298754A1/en not_active Abandoned
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1455149A1 (en) * | 2003-03-07 | 2004-09-08 | Linde Kältetechnik GmbH & Co.KG | A connection-ready refrigerator and arrangement of such a refrigerator |
| EP2091314A3 (en) * | 2008-02-13 | 2011-11-02 | Hitachi Plant Technologies, Ltd. | Cooling system for electronic equipment |
| US8199504B2 (en) | 2008-02-13 | 2012-06-12 | Hitachi Plant Technologies, Ltd. | Cooling system for electronic equipment |
| EP2498025A2 (en) | 2008-02-13 | 2012-09-12 | Hitachi Plant Technologies, Ltd. | Cooling system for electronic equipment |
| EP2498024A2 (en) | 2008-02-13 | 2012-09-12 | Hitachi Plant Technologies, Ltd. | Cooling system for electronic equipment |
| EP2503866A2 (en) | 2008-02-13 | 2012-09-26 | Hitachi Plant Technologies, Ltd. | Cooling system for electronic equipment |
| US8839638B2 (en) | 2008-02-13 | 2014-09-23 | Hitachi, Ltd. | Cooling system for electronic equipment |
| US9915454B2 (en) | 2012-03-29 | 2018-03-13 | Mitsubishi Electric Corporation | Air-conditioning apparatus including heat exchanger with controlled heat exchange amount |
| WO2013145006A1 (en) * | 2012-03-29 | 2013-10-03 | 三菱電機株式会社 | Air conditioning device |
| CN102889706A (en) * | 2012-10-22 | 2013-01-23 | 合肥天鹅制冷科技有限公司 | Compression refrigeration condensation system with low-temperature startup and low-temperature operation |
| CN102889706B (en) * | 2012-10-22 | 2015-01-28 | 合肥天鹅制冷科技有限公司 | Compression refrigeration condensation system with low-temperature startup and low-temperature operation |
| CN104501440A (en) * | 2015-01-14 | 2015-04-08 | 合肥天鹅制冷科技有限公司 | Cooling liquid forced air cooling regulation system |
| CN104501440B (en) * | 2015-01-14 | 2017-01-18 | 合肥天鹅制冷科技有限公司 | Cooling liquid forced air cooling regulation system |
| CN105783331A (en) * | 2016-05-10 | 2016-07-20 | 合肥天鹅制冷科技有限公司 | Heat efficient recovery device for air source water chilling unit |
| US11268739B2 (en) * | 2018-01-12 | 2022-03-08 | Schneider Electric It Corporation | System for head pressure control |
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