Abstract:
A vertically oriented refrigerant valve in a refrigeration cycle for substantially reducing vapor bubbles mass in a liquid refrigerant flow and providing a flow modulating and shutoff function. The valve includes an outer shell having a horizontal fluid inlet perpendicular to a vertical axis passing through an inner tubular member positioned inside the outer shell and having a vertical fluid outlet at a distal end, and a condensation chamber formed between the inside surface of the outer shell and the outer surface of the inner tubular member for collecting and condensing rising vapor bubbles from the inlet refrigerant. While the vapor bubbles portion of the refrigerant is collected in the chamber, the liquid passes through a plurality of passageways through the lower portion of the inner tubular member. A slide tube selectively closes and opens one or more of the passageways to control refrigerant flow through the passageways to precisely match the instantaneous needs of the refrigeration system. An actuator will automatically spring return and shut off the valve in the event of a power failure.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to refrigeration systems and more particularly to refrigeration valves. The present invention is described herein in detail with respect to a conventional industrial refrigeration system. However, those of ordinary skill in the art to which the present invention pertains will readily recognize the broader applicability of the present invention. For example, the present invention may find application in a heat pump system or an air conditioning system or the like. 
     2. Related Art 
     Conventional refrigeration systems utilizes a recirculating refrigerant, such as ammonia, for removing heat from the low temperature side of the refrigeration system and for discharging heat at the high temperature side of the refrigeration system. The work input operating the system is provided by a motor driven compressor, which receives low-pressure gaseous refrigerant and compresses it to a high pressure. The high-pressure gaseous refrigerant is supplied to a condenser where heat is removed from the gaseous refrigerant to condense it to a liquid. The liquid refrigerant is then supplied through a control valve to an evaporator wherein heat is transferred from a heat transfer fluid to the liquid refrigerant. The gaseous refrigerant from the evaporator is then returned to the compressor for recirculation through the refrigeration system. 
     One method of feeding liquid refrigerant to the evaporator coil is known as the “recirculated” method. In this method, the evaporator is literally flooded by recirculating more liquid than the coils can evaporate. Evaporator coils work at optimum efficiency when their entire surface remains wet with liquid refrigerant. During the refrigeration cycle, a portion of the liquid in the evaporator is vaporized into gas. Gas and liquid exit the evaporator and are sent to a gas/liquid separator known as a recirculator. Liquid from the recirculator is sent to the evaporator. 
     Additionally, a receiver drum can be added between the condenser and the control valve to collect liquid refrigerant and absorb system flow fluctuation. The liquid refrigerant is sent to the control valve to decrease the pressure and temperature of the liquid refrigerant, which is then sent to the recirculator to flood the evaporator. 
     Conventional means of control consist of a solenoid valve followed by a throttling valve to reduce the pressure and govern the flow rate. There are several drawbacks to conventional means. The refrigerant flow, and hence the load due to flash gas, is intermittent, causing pressure fluctuations, which are detrimental to pump shaft seals and compressor capacity controls. Additionally, the combination of friction losses and ambient heat gain in the high-pressure liquid line preceding the control valve cause vaporization of some portion of the refrigerant producing vapor bubbles. Such vapor bubbles interrupt and reduce the mass flow rate of any throttling valve. Furthermore, the solenoid and throttling valve combination requires the use of numerous fittings and welds. 
     It is apparent that there is a need for a refrigerant control valve that smoothly modulates the flow of refrigerant, reduces the effect of vapor bubbles and has the capacity to control large systems with a single valve that is both slow closing and tight seating. 
     Therefore, it is an object of the present invention to provide a refrigeration valve that substantially eliminates vapor bubbles in the liquid refrigerant. 
     It is another object of the present invention to provide a refrigeration valve which functions as a shutoff valve, with or without a control signal or actuator power. 
     It is a further object of the present invention to provide a refrigeration valve that includes a condensation chamber for vapor bubbles flowing with liquid refrigerant. 
     Still another object of the invention is to provide a vertically oriented control valve to provide a chamber for entrained vapor in the liquid refrigerant to be collected and condensed. 
     Yet is another object of the present invention to provide a vertically oriented refrigeration valve that closes to a tight shutoff upon a loss of power. 
     It is an additional object of the present invention to smoothly regulate the flow of refrigerant in the system in response to the real time demand. 
     Other objects include the provision of ceasing fluid flow with one seal prior to fully seating on another seal to reduce wear on the seating seal. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is directed to a valve for use in a refrigeration system. The valve comprises an elongated housing having a longitudinal axis extending generally vertically and the housing has an inlet that extends generally perpendicular to the axis for receiving a high-pressure liquid refrigerant having traces of entrained vapor bubbles and an outlet for discharging liquid refrigerant and the flashgas generated from the drop in pressure through an outlet directed generally in the same direction as the axis. The housing further includes an upright outer shell having outside and inside surfaces, and an elongated upright inner hollow tubular member positioned inside the outer shell with its longitudinal axis coincident with the axis of the housing. The tubular member has an outer and inner surfaces and proximal and distal ends. The inside surface of the outer shell and the outer surface of the tubular member join to form a vapor bubbles condensation chamber. The chamber includes a collar mounted on the distal end of the tubular member and being affixed to and adjacent the inside surface of the outer shell. The outer shell includes an upper portion and a lower portion. The lower portion has top and bottom end sections wherein the high-pressure liquid refrigerant inlet is generally located medially between the end sections. The upper portion has top and bottom end sections wherein the top end section is part of the vapor bubbles condensation chamber. The tubular inner member has a plurality of vertically spaced passageways extending generally perpendicular to the axis and through the inner and outer surfaces of the tubular inner member. These passageways are located below the bubbles condensation chamber, thus ensuring pure liquid adjacent to the passageways. The tubular member has a long axis substantially coincident with the longitudinal axis. The outlet of the housing is spaced above an outlet of the tubular member and fluidly communicates with each other. The tubular inner member has a slide tube positioned outwardly of the tubular member for selectively closing and opening one or more of the passageways to permit high-pressure liquid refrigerant to pass therethrough in response to the system load requirements and discharge through the outlet. The tubular member includes a ring seal located spacedly above all of the passageways. The slide tube has an upper end portion, which completely closes against the seal to maintain the valve inoperative with the pressurized liquid and vapor refrigerant maintained within the valve housing. The slide tube has distal and proximal ends and includes a lip seal attached to and located adjacent the distal end of the slide tube for sealingly engaging the outer surface of the tubular member during sliding movement of the slide tube in closing and opening one or more of the passageways. The valve further includes a ring disk for sealing between the slide tube and the outer surface of the tubular member. 
     The valve also includes a movable flow controller means for moving the slide tube. The controller means includes an actuator positioned beneath and to the slide tube for moving the slide tube between open and closed positions. The open position involves exposing one or more of the passageways of the tubular member to permit pressurized liquid to pass therethrough and through the outlet in response to the system load while the closed position blocks flow through the tubular member. The valve is coupled between a receiver of a condenser and a recirculator of an evaporator in a refrigeration cycle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features which are believed to be characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings, in which: 
     FIG. 1 shows a conventional refrigeration cycle including the refrigeration valve in accord with the present invention; 
     FIG. 2 shows an enthalpy v. pressure graph illustrating enthalpy and pressure change across the refrigeration valve; 
     FIG. 3 shows a cross-section of the refrigeration valve; 
     FIG. 4 is a detailed cross-section of the valve illustrating the sliding movement of the slide tube; 
     FIG. 5 show the flow controller means or the actuator; and 
     FIG. 6 shows the control mechanism of the valve. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The features and design of the invention are best understood by reference to the attached drawings. 
     FIG. 1 shows a refrigeration cycle  10  preferably using an ammonia refrigerant for removing heat from the low temperature side of the refrigeration system and for discharging heat at the high temperature side of the refrigeration system. The cycle begins with the compressor  11  that receives low-pressure gas refrigerant, which is supplied to a condenser  12 . The condenser  12  removes heat from the gaseous refrigerant, causing it to condense. This condensed refrigerant drains to the receiver  13 , which collects the refrigerant, and functions as a surge vessel for fluctuating flow rates. Liquid refrigerant from the receiver  13  is sent to the control valve  14 . In this valve any entrained vapor bubbles are collected and condensed while the flow rate of the liquid refrigerant is regulated and the pressure and temperature are reduced. The liquid refrigerant is then sent to a recirculator  15  that floods evaporators  16  via pump  15 A. The recirculator  15  sends more liquid than the evaporator coils can evaporate to force the evaporators  16  to work at optimum efficiency because the evaporators  16  work most efficiently when their entire surface remains wet with liquid refrigerant. A portion of the liquid in the evaporators  15  is vaporized into gas, which is returned to the recirculator  15  along with the excess liquid. The liquid is separated from the vapor in the recirculator  15  and returned back to the evaporators  16 . The separated vapor exits the recirculator  15  to the compressor  11  to be compressed, thus completing the cycle. 
     The thermodynamic cycle of the refrigeration system will be explained in further detail with reference to FIG. 2, which shows the phase changes in the refrigerant as it moves through the refrigeration cycle. The refrigerant saturation curve  50  is shown in FIG. 2, wherein pressure is plotted against enthalpy. The liquid line  51  is depicted on the left hand side of the saturation curve  50 , while the vapor line  52  is depicted on the right hand side of the curve. Initially, slightly superheated vapor enters the compressor  11  from the evaporators  16  via the recirculator  15  at state point A and is compressed to a higher discharge pressure at state point B. The compressed gas enters the condenser  12  where the refrigerant is reduced at constant pressure from a superheated vapor to a liquid at state point C and the heat of condensation is transferred to the coolant passing through or over the condenser heat exchanger tubes. Liquid refrigerant drains to the receiver  13 . 
     Liquid refrigerant having traces of vapor then enters the valve  14  at state point C′ and undergoes an expansion at constant enthalpy as it passes through the valve  14  to a lower pressure and temperature at state point C″. Liquid and vapor refrigerant is then sent to the recirculator  15  to separate gas from liquid. The separated liquid at state point D is pumped to the evaporators  16 . A portion of the liquid is vaporized and returned to the recirculator  15  along with the excess liquid. In the recirculator  15 , the vapor is separated, state point A and sent to the compressor  11 . The separated liquid state point D, is also pumped to the evaporators  16 . 
     FIG. 3 shows the refrigeration valve  14  of the present invention. The valve  14  comprises a housing  20  having a longitudinal axis  100  extending generally vertically and includes an outer shell  31  and an inner hollow tubular member  32  inside the outer shell  31 . The outer shell  31  is comprised of an upper portion  44  having a top and bottom end sections  46  and  47  and a lower portion  45  having top and bottom end sections  48  and  49 , wherein a fluid inlet  22 , having a flow temperature of about 75-95° F. and a pressure of about 125-180 psig is located medially between the top and bottom end sections  48  and  49 , and a fluid outlet  23  being the top end section  46  of the outer shell  31 . The top end section  46  has a diameter D 1  that increases toward the bottom end section  47  forming a bottleneck until the bottom end section  47  meets the top end section  48  that has a diameter D 2 . The lower portion  45  has a uniform diameter D 2  from the top end section  48  until the bottom end section  49  except where the inlet  22  meets the outer shell  31 . 
     The inner hollow tubular member  32  is positioned inside the outer shell  31  and has a long axis substantially coincident with the longitudinal axis  100  and includes a proximal end  53  and a distal end  54  where the vapor bubbles condensation chamber  30  is mounted so that vapor bubbles entrained in the refrigerant flow coming through inlet  22  rise to and condense on the cold surface of the vapor bubbles chamber  30 . The chamber  30  includes a collar  29  having an upper end  29 A mounted on the distal end  54  of the tubular member  32  and being affixed to and adjacent the inside surface  34  of the outer shell  31 . The threaded portion  56  of the tubular member  32  is tightened on threaded portion  56 A of the collar  29  and seals against flat Teflon® washer  39 . The lower end  29 B of the collar  29  and the distal end  54  of the tubular member  32  being spaced inwardly from the inside surface of the outer shell  31  to cause rising vapor bubbles to condense thereon, and thereby substantially reduce number and volume of vapor bubbles in the medial area of the housing  31  ensuring a continuous, uninterrupted and smooth pure liquid flow into the passageways  37 . 
     While the vapor bubble portion of the liquid is collected in the chamber  30  and condensed, the liquid passes through the passageways  37  substantially free of vapor bubbles to exit through the outlet  23 . The vapor percentage at this point is 10-20% by mass with a temperature of about 10 to 20° F. and a pressure of 25-33 psig. There is a variant of these conditions in a two stage refrigeration system where the high side and low side pressures are in the 25 to 33 psig and 0 psig to 15″ Hg vacuum, respectively. 
     FIG. 4 shows the inner tubular member  32  in detail. The inner tubular member  32  has a plurality of vertically spaced passageways  37  extending generally perpendicular to the longitudinal axis  100  extending generally vertically through the inner tubular member  32 . The passageways  37  extend through the inner surface  36  and the outer surfaces  35  for permitting liquid refrigerant to pass therethrough. The passageways  37  are below the vapor bubbles condensation chamber  30 , ensuring the presence of pure liquid at the entrance of the passageways  37 . 
     The passageways  37  are spaced and extend through the inner surface  36  in a helical path  37 A that spirals 360° around member  32 . Another helical path  37 B spirals for 360° as another set of passageways  37  through the inner surface  36 . The passageways  37  may be {fraction (3/32)} inches and spaced approximately 15 degrees apart on centers. The passageways  37  in member  32  are preferably arranged in a pattern that allows an approximately linear increase in flow rate as the passageways  37  are uncovered by the slide tube  38 . The passageways  37  are arranged in a diametrically opposed pattern to reduce the impingement erosion of the inside of the tubular member  32 . The size, quantity and arrangement of the passageways  37  may be varied to change the flow coefficient of the valve in response to the capacity required and the refrigerant used in the system. 
     A slide tube  38  is located outwardly of the tubular member  32  for selectively closing and opening one or more of the passageways  37 . The slide tube  38  is movable between a closed position (x), as shown in FIG. 4, and an open position, such as (y), exposing two or more passageways  37  to liquid refrigerant. The slide tube  38  includes nose section  26  at its distal end  38 A abutting quad O-ring seal  24  attached to the outer surface  35  of the tubular member  32  to prevent any fluid leakage therefrom. It is to be noted that when the valve is closing, the ring disks  25  seal off the flow of the refrigerant from passing through any passageways  37  prior to being seated on seal  24  so that substantial reduction in wear on seal  24  is achieved. 
     In the closed position (x), the nose section  26  abuts the quad O-ring seal  24  while in the open position, such as (y), the nose section  26  occupies a new position  26 A to expose one or more of the passageways  37  to liquid refrigerant. 
     The nose section  26  is the upper edge of a collar  43 , which is threadedly secured to the slide tube  38  to squeeze a pair of stainless steel ring washers with three Teflon® ring disks  25  so that the disks  25  seal against the inner tubular member  32 . The slide tube  38  also includes lip seal  28  to seal against the inner tubular member  32  along with nylon wear bushing  27 . 
     FIG. 5 shows the flow controller means or the actuator  40 . The actuator  40  is enclosed by a cap  64 . The actuator  40  is pivotally joined to the proximal end  53  of the tubular inner member  32  by an arm  41  that extends into subassembly  66 , and is attached to a rocker arm  61  of a shaft  63  by a pivot joint  62 . A bushing  42  is mounted around the shaft  63 , which is enclosed in a gasket  65 . The rocker arm oscillates between its original position, as shown in FIG. 5, and position  61 A, shown in dotted lines, when the shaft  63  rotates upon receiving electrical signals through the wires  68 . The movement of the rocker arm  61  pushes the slide tube  38  vertically upwardly and downwardly exposing one or more of the passageways  37  to liquid refrigerant flow, to modulate the flow of refrigerant in response to the system load. If the electricity is cut off, the coil spring (not shown) within the actuator  40  turns the shaft  63  which pushes the rocker arm  61  upwardly causing the slide tube  38  to block the passageways  37  preventing liquid flow therethrough, thereby providing a shut off function and eliminating the need for a liquid line solenoid valve. The outer shell  31  is filled with liquid refrigerant at all times, and liquid can seep through the proximal end  53  of the tubular member  32  up to lip seal  28 . Actuator  40  may be of the commercially obtained, for example, from Belimo Aircontrols (USA), Inc., proportional control actuator NF24-SR US. 
     FIG. 6 shows the electrical control mechanism of the valve  14 , which is a simple linear control mechanism. The liquid level in the recirculator  15  is measured by a capacitance level transmitter  69 , which is connected to a level transducer  70  that produces output signals. The recirculator  15  operates between 10% (minimum) and 20% (maximum) feed level. The transducer  70  produces a 4-20 ma signal output to a controller  71 . When the liquid level in the recirculator  15  is at a level of 10%, the transducer  70  produces a 5.6 ma output signal to the controller  71 , which transforms it to a 10 v dc voltage signal, which is sent through wires  68  to the motor  72  that turns the shaft  63  causing the rocker arm  61  to move downwardly to position  61  A causing the slide tube  38  to fully expose the passageways  37  to liquid refrigerant flow. 
     At 20% liquid level in the recirculator  15 , the transducer  70  produces an output signal of 7.2 ma, which is sent to the controller  71  that transforms it to voltage output of 2 v dc, which is sent to the motor that turns the shaft  63  causing the rocker arm  61  to move upwardly from its position  61 A causing the slide tube  38  to fully close the passageway  37  blocking any liquid flow. The relationship between the system limits is linear and inversely proportional. For example, 7.2 ma produces a 2 v dc voltage, 6.4 ma produces a 6 v dc voltage and 5.6 ma produces a 10 v dc voltage. 
     While the invention has been described with respect to certain specific embodiments, it will be appreciated that many modifications and changes may be made by those skilled in the art without departing from the spirit of the invention. It is intended therefore, by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention.