WO2015171809A1 - Capteur de serpentin de dégivrage dans un évaporateur de système de réfrigération - Google Patents

Capteur de serpentin de dégivrage dans un évaporateur de système de réfrigération Download PDF

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Publication number
WO2015171809A1
WO2015171809A1 PCT/US2015/029528 US2015029528W WO2015171809A1 WO 2015171809 A1 WO2015171809 A1 WO 2015171809A1 US 2015029528 W US2015029528 W US 2015029528W WO 2015171809 A1 WO2015171809 A1 WO 2015171809A1
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WO
WIPO (PCT)
Prior art keywords
pipe
refrigerant
rods
evaporator
another
Prior art date
Application number
PCT/US2015/029528
Other languages
English (en)
Inventor
Greg DEROSIER
Original Assignee
Evapco, Inc.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Evapco, Inc. filed Critical Evapco, Inc.
Priority to CA2947437A priority Critical patent/CA2947437A1/fr
Priority to MX2016014539A priority patent/MX2016014539A/es
Priority to EP15788701.9A priority patent/EP3140600A4/fr
Publication of WO2015171809A1 publication Critical patent/WO2015171809A1/fr

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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
    • 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
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/02—Detecting the presence of frost or condensate
    • 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
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/002—Defroster control
    • F25D21/006—Defroster control with electronic control circuits
    • 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
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/06—Removing frost
    • 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
    • F25B2700/11—Sensor to detect if defrost is necessary
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/226—Construction of measuring vessels; Electrodes therefor

Definitions

  • This invention relates primarily to industrial or commercial refrigeration systems. Specifically, this invention relates to systems for detecting an accumulation of frost on an evaporator and initiating a defrost cycle when the accumulation of frost reaches unacceptable levels.
  • frost is a thermal insulator.
  • frost is a thermal insulator.
  • the buildup of frost restricts the air flow through the evaporator coils. As a result, less air is cooled.
  • frost builds up, the combined effects of reduced air flow and reduced heat transfer require that the evaporator be defrosted to restore cooling efficiency.
  • frost detection systems such as those shown in U.S. Pat. Nos. 4,045,971 and 4,232,528, employ photoelectric sensors to detect the level of frost buildup on an evaporator coil.
  • the system in U.S. Pat. No. 4,831,833 uses an air velocity sensor in the air flow path to determine whether defrost should be initiated.
  • Another prior art system senses the differences in air temperature on each side of the evaporator in the refrigerated space as well as the temperature of the refrigerant leaving the evaporator. The data from the sensors is processed to determine if there is a frost buildup requiring the initiation of the defrost cycle.
  • timed defrost systems The problem with prior art timed defrost systems is that the amount of water vapor in the air in the refrigerated area varies depending on a number of factors. Some of these factors include the humidity in the environment surrounding the space being cooled, the number of times the access door to the refrigerated area is opened, and the duration of such openings. The temperature in the area being cooled, the temperature of the evaporator, the velocity of the air passing through the evaporator and the evaporation of water from items stored in the cooled area, are all factors that also affect the rate of frost buildup. Usually, timed defrost systems must be set for the severe conditions when frost will accumulate most rapidly.
  • frost buildup also impact the power requirements for a fan motor.
  • factors other than frost buildup include the supply voltage, the temperature in the cooled space, and the age of the motor.
  • the system described in the '949 patent also has the disadvantage that the characteristics of refrigeration system components vary with age and loss of refrigerant. Such a system cannot compensate for these factors.
  • frost detection systems that rely on photoelectric sensors, such as that disclosed in the '971 patent, are only capable of sensing frost at a particular location on an evaporator.
  • frost buildup is not always regular or uniform, frost may build at locations away from the photoelectric sensor and not be detected. This will cause the evaporator to operate inefficiently because defrosting may be needed even though it is not detected due to the location of the sensors.
  • frost may build up near the sensor to a greater extent than at other locations causing defrost to be initiated when it is not needed.
  • Another deficiency of such systems is that they may not detect the buildup of transparent, clear ice.
  • the system in the '833 patent suffers from similar location-dependent deficiencies.
  • the present invention is an improved method and system for detecting and preventing the capacity reduction impact of frost building on a coil surface.
  • prior methods have relied on air side pressure increase, surface frost optical detection, air side temperature change with time, fan power increase or other external measures that indirectly indicate frosted coil performance reduction.
  • This invention relies on detecting a change in the amount of internal refrigerant liquid that is evaporated by the heat exchanger, and/or changes in the ratio of refrigerant liquid to refrigerant vapor.
  • the invention may be used to initiate coil defrost in any evaporating refrigerant cooling system, including direct expansion and liquid overfeed evaporators.
  • overfeed evaporator coil In an overfeed evaporator coil, more liquid is introduced into the coil than is evaporated by the coil. The excess liquid is called overfeed, which returns to the low pressure side accumulator. By overfeeding the evaporator, the inner surface is kept thoroughly wetted and thus achieves optimum heat transfer.
  • the ratio of liquid refrigerant to evaporated refrigerant in the vapor phase is referred to as the liquid mass ratio.
  • the evaporative efficiency declines, and as the evaporative efficiency declines, less refrigerant is evaporated, and the liquid mass ratio increases.
  • the liquid mass ratio is measured with a suitable sensor, including but not limited to a void fraction sensor.
  • the sensor produces an output signal that is reflective of the amount of liquid in the refrigerant flow stream.
  • the sensor and its control system can measure a first or initial or full defrost liquid mass ratio, and use that ratio as the starting point for determining the trigger point for a defrost cycle. As a coil builds frost, the liquid mass ratio increases.
  • a control When the increase in liquid mass ratio exceeds a specified value, that is, a predetermined increase over the first/initial/full defrost value, a control will signal that defrost of the coil is required.
  • the system can initiate defrost automatically upon receipt of such signal, or can be configured to alert a system operator to manually authorize system defrost.
  • the control system may optionally measure the liquid mass ratio, compare it to a first/initial liquid mass ratio and/or to a previous full defrost liquid mass ratio, and optionally use the new ratio, or optionally an average of prior full defrost liquid mass ratios, to use as the starting point for determining the trigger point for the next defrost cycle.
  • the system can be dynamic as it constantly adjusts to actual site and system conditions, and thus takes into account such factors as the age and possible loss of refrigerant.
  • the control system can also use input from the liquid mass ratio sensor to detect if an evaporator is operating at an optimum overfeed rate. The overfeed rate may not be optimum due to liquid feed valve settings or a reduction in heat transfer unrelated to frost on the coil.
  • the operator can manipulate the trigger point to meet specific requirements based on system priorities.
  • the defrost trigger point might be set low (e.g., when the liquid mass ratio is 5% over the first/initial/full defrost liquid mass ratio), when just a little bit of frost is starting to form, if high performance/efficiency (frost inhibits performance) is required.
  • the defrost trigger point might be set higher if some capacity loss is acceptable and/or fewer defrost cycle events is desired.
  • a frost detection system for an evaporator which senses frost buildup by measuring the liquid mass ratio in or exiting from the evaporator coil.
  • a liquid mass ratio sensor is located in the evaporator coil.
  • a liquid mass ratio sensor is located between the evaporator coil and the compressor.
  • a frost detection system which need not take into account temperature in the refrigerated area.
  • a frost detection system that need not take into account changes in the operating characteristics of the refrigeration equipment due to aging.
  • the frost detection system may be provided with a device that measures the heat load of the system, for example the air temperature into the coil relative to coil saturation temperature or the total flow rate of refrigerant (both liquid and vapor), and the heat load information is used to adjust the defrost point for specific liquid mass ratios detected by the liquid mass ratio sensor.
  • a frost detection system that is more accurate, reliable and less expensive to implement that existing systems.
  • a method for controlling and/or initiating the defrost cycle of an evaporative coil having the following steps: detecting the ratio of liquid refrigerant to refrigerant in a vapor phase; and initiating a defrost cycle when the ratio of liquid refrigerant to vapor phase refrigerant equals or exceeds a predetermined amount.
  • the predetermined amount may be changed according to operator preference.
  • a first ratio of liquid refrigerant to vapor phase refrigerant may be determined when said evaporative coil has no frost.
  • a defrost cycle may be initiated when the detected liquid to vapor mass ratio is an amount higher (e.g., 5%, 10%, 15%) than said first liquid to vapor mass ratio.
  • a method for controlling and/or initiating the defrost cycle of an evaporator having the following steps: detecting a first capacitance between charged plates situated in the coil of an evaporator, or downstream of the coil; detecting a second capacitance between the charged plates; and initiating a defrost cycle when a difference between the first capacitance and the second capacitance equals or exceeds a predetermined amount.
  • the predetermined amount may be changed according to operator preference.
  • the difference between said first capacitance and said second capacitance corresponds to a difference in volumes of fluid passing between said charged plates.
  • the first capacitance is determined when said evaporator has little or no frost.
  • the method is used in a liquid overfeed evaporator, but it may also be used in other systems including direct expansion systems.
  • an apparatus for initiating coil defrost in an evaporator including a refrigerant evaporating heat exchange coil and a sensor for detecting the ratio of liquid refrigerant to refrigerant in a vapor phase.
  • Said sensor may be located in said coil, or between said coil and a condenser of said evaporator, more particularly between said coil and a compressor of said evaporator, and more particularly between said coil and a separator of said evaporator.
  • the refrigerant evaporating heat exchange coil is in a liquid overfeed evaporator.
  • an apparatus for initiating coil defrost in a refrigeration system including a refrigerant evaporating heat exchange coil and a liquid mass ratio sensor located in the coil, or downstream of said coil, wherein said liquid mass ratio sensor is a capacitance sensor.
  • the liquid mass ratio sensor may include a plurality (two or more) of spaced apart conductive elements conductively connected to a current source. According to this embodiment, the sensor detects changes in capacitance due to changes in the amount of liquid between the spaced apart conductive elements. According to a further embodiment of the invention, the liquid mass ratio sensor is a parallel plate sensor.
  • the liquid mass ratio sensor is made of parallel plates configured to receive a charge, and where the sensor is configured to take capacitance readings that reflect a volume of liquid passing between the plates of the sensor.
  • the conductive elements may take the form of coils, cylinders, or other shapes.
  • the conductive elements of the sensor may be in the form of parallel concentric cylinders.
  • a first part of the capacitance sensor is the metal wall of the pipe through which the refrigerant is passing, and a second part of the capacitance sensor is an electrode situated in the interior of the pipe.
  • the internal electrode portion of the sensor consists of a plurality of parallel metal rods covered in an insulating material such as PTFE (Teflon). The rods are electrically connected together on one end. An electrical connection is made to an external electronics unit through an insulating pressure tight fitting.
  • the parallel rods are arranged in an arc spaced a radial distance from the inside pipe surface by insulating spacers located at each end of the rods.
  • the parallel rods are arranged in a plane across the interior space of the pipe.
  • the spacers and rods allow for free liquid flow under the rods (between the rods and the inside surface of the pipe).
  • the rods and the metallic pipe make a capacitive type sensor that is responsive to the amount of refrigerant flowing between the rods and pipe wall.
  • Figure 1 shows a perspective view of a sensor according to an embodiment of the invention.
  • Figure 2 shows an end view of the sensor shown in Figure 1.
  • Figure 3 shows a cross-sectional view of the sensor shown in Figures 1 and 2.
  • Figure 4 is a representation of a refrigerant evaporating cooling system having a sensor according to an embodiment of the invention.
  • Figure 5 shows an end view of a capacitance sensor electrode according to an embodiment of the invention.
  • Figure 6 shows a cut-away perspective view of a capacitance sensor electrode according to the embodiment shown in Figure 5.
  • Figure 7 shows a side perspective view of the capacitance sensor electrode shown in Figures 5 and 6, removed from the pipe.
  • Figure 8 shows an end view of a capacitance sensor electrode according to a different embodiment of the invention.
  • Figure 9 shows a cut-away perspective view of a capacitance sensor electrode according to the embodiment shown in Figure 8.
  • Figure 10 shows a side perspective view of the capacitance sensor electrode shown in Figures 8 and 9, removed from the pipe.
  • Figure 1 shows a sensor 2 according to one embodiment of the invention.
  • the sensor shown in Figure 1 works on the basis of capacitance change due to the amount of liquid refrigerant between two charged plates. As mentioned above, this is only one embodiment of the invention according to which the amount of liquid refrigerant in the coil or leaving the coil may be determined according to any number of known methods.
  • the capacitance sensor includes charged plates in the form of concentric cylinders, 6 and 8, see Figures 2 and 3.
  • the sensor shown in Figures 1-3 is a 2-inch HBDX-SAM-Mark void fraction sensor (in gas-liquid two-phase flow, the void fraction is defined as the fraction of the flow-channel volume that is occupied by the gas phase or, alternatively, as the fraction of the cross-sectional area of the channel that is occupied by the gas phase).
  • the HBDX-SAM-Mark sensor may be purchased from HB Products of Denmark, but any sensor that detects capacitance change between charged elements due to changes in the amount of liquid between them can be used according to the capacitance detection embodiment of the invention.
  • Cylinder 6 is held in the refrigerant flow path of cylinder 8 (which may also serve as the sensor housing) by stacks 12.
  • Stacks 12 are conductive ly connected to charged cylinders 6 and 8.
  • the capacitance change which is very small, is detected by a sophisticated electronic circuit 18 and then output in a useable signal to control system 20.
  • the sensor may include additional concentric cylinder 4, held in the refrigerant flow path of cylinder 8 by supports 10, and capacitance changes between cylinders 4 and 6, between cylinders 4 and 8, or between cylinders 4, 6 and 8 may be used to compare changes in the amount of liquid between them over time.
  • a first part of the capacitance sensor is the metal wall of the pipe through which the refrigerant is passing, and a second part of the capacitance sensor is an electrode 22 situated in the interior of the pipe.
  • the internal electrode portion 22 of the sensor consists of an array of a plurality of parallel metal rods 24 covered in an insulating material such as PTFE (Teflon) supported in support elements 26.
  • support elements 26 are plastic, and the surface of the support elements 26 that face the rods define a plurality of recesses 25 configured to receive and hold the rod ends in fixed and spaced positions.
  • the support elements may be held together by a connecting rod 29 connecting the support elements and drawing them together, either by threading through a threaded hole 31 in the supports, or by passing through a hole in the supports into a threaded nut, or by any other known method.
  • the rods are electrically connected together at one end.
  • the rods may be solid or they may be hollow.
  • the rods may have a cylindrical cross section, as shown in Figure 5, or they may have a cross-section having a different shape, including square, elliptical, pentagonal, hexagonal, etc.
  • the rods may be arranged in an arc proximate to the inside surface of the pipe as shown in Figure 5, or they may be arranged in a plane across the interior space of the pipe as shown in Figures 5-7.
  • the diameter of the rods in the embodiment shown in Figure 5 is 0.1875 inches, and the radial distance between the centerline of the metal portion of the rod and the inside of the pipe is about .375 inches.
  • the spacing between the rods and the pipe affects sensitivity, flow thickness measurement, and sensor output range.
  • a closer rod-to-wall distance increases sensitivity but can affect the flow stream if the liquid impacts the sensor structure, and can also decrease sensor output range with thicker liquids.
  • Preferred spacing between the centerline of the rod and the inside surface of the pipe is considered to be between 0.1 inches and 0.5 inches, with more preferred spacing at 0.25 inches to 0.45 inches, and most preferred spacing at 0.35 inches to 0.375 inches.
  • Other spacing between rods and pipe surface may be used according to different sensitivity, liquid thicknesses, and sensor output range considerations and requirements.
  • the rods 24 shown in Figure 5 have a length of about 10.5 inches, but they may be of any convenient length. Longer rods make the capacitor plate area higher, which in turn increases the sensitivity of the sensor.
  • the number of rods shown in Figure 5 was selected to cover about a third of the circumference of the pipe in which they are situated.
  • the rods are electrically connected to an external electronics unit with insulated wires 27 through an insulating pressure tight fitting 30.
  • the parallel rods of Figure 5 are spaced a radial distance from the inside pipe surface by insulating spacers 28 located at each end of the rods. The spacers and rods allow for free liquid flow under the rods (between the rods and the inside surface of the pipe). Together, the rods and the metallic pipe make a capacitive type sensor that is responsive to the amount of refrigerant flowing between the rods and pipe wall.
  • Figures 8-10 show an alternative embodiment of the invention according to which the rods are arranged in a plane across the internal space of the pipe. Figures 8-10 show a larger number of smaller diameter pipes, according to another embodiment of the invention.
  • the liquid mass ratio sensor of the invention may be placed in the coil of the evaporator 14 (see Fig. 4), or it may be placed downstream of the evaporator, for example at location 16.
  • the sensor orientation may be vertical, horizontal or some other angle. Whatever the orientation, the sensor is preferably exposed to the liquid and vapor flow in the evaporator or downstream of the evaporator, and the sensor response is reflective of actual changes in the amount of liquid refrigerant evaporated.
  • the user may select a particular sensor output for defrost initiation depending on the cost of initiating a defrost cycle (cost of system down-time) relative to the savings gained through capacity increase as a result of defrost.
  • the selected point for defrost initiation may vary with evaporator application and to user sensitivity to cost and/or efficiency. It is estimated that the capacity reduction (loss of cooling power/efficiency) due to frost effects can range from 5% to 25% or more.
  • the system of the invention may be set to initiate a defrost cycle when the sensor detects a change in the liquid mass ratio of 5%, 10%, 15%, 20% or more, which may correspond to reductions in capacity of anywhere from 5% to 25%.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Defrosting Systems (AREA)

Abstract

L'invention concerne un système de commande du cycle de dégivrage d'un évaporateur, comprenant un capteur dans le serpentin d'un évaporateur ou en aval du serpentin, ce capteur étant configuré pour déterminer des changements du rapport massique liquide du réfrigérant dans l'évaporateur. La différence du rapport massique liquide indique l'accumulation de givre sur l'extérieur de l'évaporateur. Lorsque la différence de rapport massique liquide atteint une quantité prédéterminée correspondant à une accumulation de givre non satisfaisante, un cycle de dégivrage est lancé. Lorsque le rapport massique liquide revient à une valeur correspondant à un évaporateur dégivré, le cycle de dégivrage est interrompu.
PCT/US2015/029528 2014-05-06 2015-05-06 Capteur de serpentin de dégivrage dans un évaporateur de système de réfrigération WO2015171809A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
CA2947437A CA2947437A1 (fr) 2014-05-06 2015-05-06 Capteur de serpentin de degivrage dans un evaporateur de systeme de refrigeration
MX2016014539A MX2016014539A (es) 2014-05-06 2015-05-06 Sensor para la descongelacion de bobina en un evaporador de sistema de refrigeracion.
EP15788701.9A EP3140600A4 (fr) 2014-05-06 2015-05-06 Capteur de serpentin de dégivrage dans un évaporateur de système de réfrigération

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US201461989080P 2014-05-06 2014-05-06
US61/989,080 2014-05-06
US14/705,781 US20160018154A1 (en) 2014-05-06 2015-05-06 Sensor for coil defrost in a refrigeration system evaporator
US14/705,781 2015-05-06

Publications (1)

Publication Number Publication Date
WO2015171809A1 true WO2015171809A1 (fr) 2015-11-12

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PCT/US2015/029528 WO2015171809A1 (fr) 2014-05-06 2015-05-06 Capteur de serpentin de dégivrage dans un évaporateur de système de réfrigération

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US (1) US20160018154A1 (fr)
CA (1) CA2947437A1 (fr)
MX (1) MX2016014539A (fr)
WO (1) WO2015171809A1 (fr)

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EP3027629B1 (fr) * 2013-07-31 2017-06-14 UDC Ireland Limited Complexes de carbène-métal diazabenzimidazole luminescent
CA3046495A1 (fr) 2016-12-12 2018-06-21 Evapco, Inc. Systeme de refrigeration d'ammoniac integre a faible charge avec condenseur evaporatif
CN107490607B (zh) * 2017-06-29 2021-03-23 芯海科技（深圳）股份有限公司 一种利用蒸发管作为电极的凝霜传感器

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WO2011148413A1 (fr) * 2010-05-26 2011-12-01 三菱電機株式会社 Dispositif de réfrigération et de climatisation
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US4736635A (en) * 1986-02-14 1988-04-12 Aichi Tokei Denki Co., Ltd. Electromagnetic flowmeter
US5410887A (en) * 1992-10-01 1995-05-02 Hitachi, Ltd. Apparatus for detecting composition of refrigerant and method therefor
US6264898B1 (en) * 1997-11-19 2001-07-24 The Titan Corporation Pulsed corona discharge apparatus
US20020088238A1 (en) * 2001-01-05 2002-07-11 Holmes John S. Deterministic refrigerator defrost method and apparatus
US6715304B1 (en) * 2002-12-05 2004-04-06 Lyman W. Wycoff Universal refrigerant controller
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US20110214438A1 (en) * 2008-09-05 2011-09-08 Danfoss A/S Method for controlling a flow of refrigerant to an evaporator
US7628080B1 (en) * 2008-09-09 2009-12-08 Murray F Feller Magnetic flow meter providing quasi-annular flow
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US20120047987A1 (en) * 2010-08-30 2012-03-01 Kabushiki Kaisha Toshiba Electromagnetic flow rate measurement system and calibrator therefor
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Publication number Publication date
MX2016014539A (es) 2017-08-22
US20160018154A1 (en) 2016-01-21
CA2947437A1 (fr) 2015-11-12

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