US3280592A - Method and apparatus for chilling liquid - Google Patents

Description

Oct. 25, 1966 n. J. BARDAY METHOD AND APPARATUS FOR CHILLING LIQUID 2 Sheets-Sheet 1 Filed Jan. 19, 1965 INVENTOR ATTORNEYS 35 DOIZQZCZJBCU I. I llllllllw Oct. 25, 1966 D. J. BARDAY METHOD AND APPARATUS FOR CHILLING LIQUID Filed Jan. 19, 1965 2 Sheets-Sheet 2 a/g ATTORNEYS Z61 J fiardaj M Patented Oct. 25, 1966 3,280,592 METHOD AND APPARATUS FOR CHILLING LIQUID Donald J. Bar-day, 721 16th St., Boulder, Colo. Filed Jan. 19, 1965, Ser. No. 426,556 8 Claims. (Cl. 62-399) This invention relates to a method and apparatus for chilling liquid for industrial cooling purposes, and more particularly to such a method and apparatus which utilizes an expanding refrigerant to elfect its chilling action.-

Many industries such as plastic, aerosol, dry cleaning and chemical industries utilize liquid chilling devices. These devices occupy valuable floor space. Accordingly, there is a need for a compact liquid chilling device which can operate with a high degree of elficiency while still being low in cost.

An object of this invention is to provide such a highly efiicient and compact liquid chilling apparatus and method which is low in original cost as well as in operational and maintenance costs.

A further object is to provide such a device which may easily be moved from one location to another.

In accordance with this invention, the expanding refrigerant and the liquid to be cooled are circulated through coaxial tubing in the liquid storage tank of the chilling device. The cooling effect of the expanding refrigerant is uniquely utilized not only to cool the liquid being discharged from the chilling device but also to pre-cool the liquid stored in the tank. This is accomplished by pumping the reserve or stored liquid through the inner of the coaxial tubing before it is discharged to, for example, a molding machine and returned to the tank as reserve liquid. The expanding refrigerant is circulated in the outer of the coaxial tubing in the storage tank. Accordingly, the expanding refrigerant not only cools the liquid in the inner tubing but also pre-cools the reserve liquid stored in the tank. Additionally, arranging the coaxial tubing in the same storage tank as the reserve liquid results in a conveniently compact liquid chiller while still attaining a maximum degree of efliciency by virtue of the dual cooling of the expanding refrigerant.

In an advantageous form of this invention the coaxial tubing is arranged in sections with outer tubing sections stacked atop each other in a parallel'relationship while the inner tubing sections Weave in and out in series through several of the parallel outer tubes. By this arrangement, the parallel refrigerant flow limits the pressure drop in the refrigerant circuit while the series flow of the chilled liquid permits high velocity turbulent flow for maximum heat transfer.

Novel features and advantages of the present invention will become apparent to one skilled in the art from a reading of the following description in conjunction with the accompanying drawings wherein similar reference characters refer to similar parts and in which:

FIG. 1 is a three-dimensional view of one embodiment of this invention;

FIG. 2 is a three-dimensional view of a portion of the embodiment shown in FIG. 1 partially broken away and in section;

FIG. 3 is a sectional view through FIG. 2 along the line 3-3; and

FIG. 4 is schematic view showing the refrigerant cycle of the embodiment of the invention shown in FIGS. 1-3.

As shown in FIG. 1 liquid chiller 10 includes a storage tank 12 for holding a reserve liquid or anti-freeze solution such as brine. Mounted beneath the storage tank 12 is pump 14 for circulating the liquid. The entire unit 10 is mounted on rollers 16 to facilitate the portability of liquid chiller 10. Tank 12 is made, for example, of stainless steel which is insulated by urethane foam. A transparent tube 18 mounted on the outside of tank 12 communicates with the interior of the tank so that the level of the liquid in tank 12 is the same as the level in tube 18. Tube 18 thereby provides a convenient means of indicating the liquid level in tank 12.

As later described pump 14 sucks liquid from the bottom of tank 12, circulates the liquid through the inner coaxial tubing in tank 12 and discharges it through outlets 20 to a heat exchange system such as a plastic molding machine. Each outlet 20 is individually controlled by a respective valve 22 to regulatethe amount of liquid flow therethrough. After the chilled liquid is used in the heat exchange system it is returned to the bottom of tank 12 through inlets 24- which are also individually controlled by valves 26.

FIG. 4 schematically illustrates the refrigerant cycle used with liquid chiller 10. As shown in FIG. 4 the refrigerant is circulated by compressor 28 through con denser 30, through filter-drier 32 and into expansion valve '34. Expansion valve 34 then distributes the expanding refrigerant into opposite ends of the outer portion of coaxial tubing 36 in tank 12 where the expanding refrigerant cools both the liquid flowing in the inner of the coaxial tubing (as later described) and the liquid stored in tank 12. Compressor 28 then sucks the refrigerant from the central portion of coaxial tubing 36. The refrige'rating system also includes a number of control features, for example, a temperature sensing bulb 38 is mounted on the outlet line 40 from the coaxial tubing 36 and isconnected to expansion valve 34 to sense the temperature of refrigerant vapor returning to the compressor 28. Additionally, an external equalizer 42 is connected between expansion valve 34 and outlet line 40 to sense refrigerantvapor pressure at the coaxial-tubing outlet. The combined effect of temperature sensed by bulb 38 and pressure sensed by equalizer 42 regulates flow of liquid refrigerant through expansion valve 34. During the normal cooling cycle, expansion valve 34 simply modulates liquid refrigerant flow in response to cooling demand at any particular instant. However, when a set temperature is reached'and further cooling is not wanted, solenoid valve 44 opens in response to a thermostat which senses outgoing brine temperature at supply manifold 66 (FIG. 2). Solenoid valve 44 opens a by-pass line commencing at a branch connection between compressor 28 and condenser 30 and terminating at the outlet manifold from coaxial tubing elements 36. The terminal point of this by-pass line is upstream from temperature sensing bulb 38 and equalizer 42. Consequently, expansion valve 34 is immediately responsive to changing conditions of increasing refrigerant vapor temperature and pressure as solenoid valve 44 opens to admit relatively hot, high pressure vapor to outlet line 40. The initial increased pressure in line '40 tends to close expansion valve 34. Within seconds, however, the in= creasing temperature sensed by bulb 38 reestablishes flo w through expansion valve 34 sufiicient to cool the relatively hot gas in line 40 thus preventing compressor 28 from overheating.

tubing 36 can be controlled within /2 F. Accordingly, the unit cooling capacity is modulated by action '.of solenoid valve 44 without off-again, on-ag-ain cycling of compressor 28 and compressor 28 can thus continuously operate. Additionally, undue abuse of compressor 28 and its electrical accessories are avoided, while the system is immediately responsive to every change in cooling requirement. The control panel also includes pressure guages to show the compressor suction and discharge pressure as well as the on-off controls for unit 10. As shown in FIG. 2 coaxial tubing 36 is conveniently made up of a plurality of tube sections. The outer tubing comprises individual helical shaped tubing sections 46, 48, 50 and 52 which are stacked atop each other in parallel relationship. The expanding refrigerant is circulated through expansion valve 34 in tank 12 into lines 54 into each end of each tubing section and 'the refrigerant is withdrawn from line 56 in ,thecentral portion of each section and returned to compressor 28 through connection line 40 as previously described.

The liquid stored in tank 12 ismaintainedat a level above coaxial tubing 36. Pump 14 sucks liquid through line 58 and discharges into line 60 which communicates with the inner tubing sections 62 and 64. Each inner I tubing section 62 and 64 weaves in and out in series through two or more of the out-ertubing sections and is discharged into multiple outlet manifold 66. By this arrangement with the refrigerant tubes in strictly parallel relationship and the liquid tubes in series in multiples of two or more elements, the pressure drop in the refrigerant cycle is limited while a high velocity turbulent liquid flow is permitted for maximum heat transfer. Additionally, the expanding refrigerant is in heat contact relationship with the inner tubing of 62 and 64 to adsorb heat from and thus cool the liquid flowing through the inner tubing. Moreover, the outer surface of the outer tubing is a prime heat transfer surface in contact with the expanding refrigerant and with the reserve liquid stored in tank 12. Advantageously, the coaxial tubing 36 is formed from, for example, copper or thin-Wall stainless steel to act as as effective heat transfer surface;

As shown in FIGS. 1 and 2 chilling device .or unit is extremely compact with the heat adsorbing tubing, expansion valve 34, chilled liquid manifold, return piping, and other related plumbing all stored in the same tank 12 which stores the reserve liquid. Additionally, the above described coaxial tubing 36 has minimum joints and is connected with a minimum amount of tubing outside insulated. tank 12. Accordingly, other than tank 12 itself, only the connecting lines 58, 60 to pump 14 and the vapor refrigerant connecting line must be insulated. Thus the cooling effect of the expanding refrigerant is conserved while damage fromleaks in the liquid lines are minimized because the liquid lines are stored within the reserve liquid.

As also shown in FIG. 1 water cooled condenser 30 is mounted on the same bracket 68 which supports tank 12, while, compressor 28 including the liquid refrigerant receiver tank (not shown) as well as pump 13 are mounted on lower plate 70 so that the entire unit 10 is easily moved from one location to another.

An additional feature is the use of a pressure switch 72, the fluid connection at which is connected to pump discharge line 60, and which is electrically connected to compressor 28 and pump 14 control circuit. Thus if liquid flow through pump 14 and coaxial tubing 36 is restricted because of ice formation in the inner tube, this switch will sense increasing pump pressure and stop operation of th entire unit. Further if all of liquid supply valves 22 or return valves 26 are closed so no flow is possible, theunit will not operate. The pressure section of the inner tube because of ice formation will cause a pressure increase in line 60 and operation of the unit will stop bfore damage occurs. Likewise, the unit cannot'be operated with all supply or return valves closed. Thus, damage to pump 14 by overheating is avoided.

A further feature is the use of a liquid relief valve, the inlet of which is connected to liquid supply manifold 66 and the outlet of which discharges directly back into reservoir tank 12. This valve :is set, for example, to maintain a manifold pressure of 40p.s.i. where pump 14 is capable of developing 45 p.-s.i. discharge pressure. This valve acts as a modulating bypass valve to maintain constant liquid supply pressure at manifold 66 within capacity of the pump. It assures liquid flow through pump14 at all times and permits test operation ofthe unit without connecting it to an external cooling load. Further, constant liquid supply pressure combined with constant liquid temperature assures closecontrol of temperature at mold or other apparatus requiring temperature control.

What is claimed is:

1. A liquid chilling device for supplying a heat exchange system with liquid cooled by :a refrigerating system employing expanding refrigerant comprising a storage tank for holding a reserve liquid to be chilled, pump means connected to, said storage tank for withdrawing liquid therefrom, coaxial tubing in said storage tank including inner tubing and outer tubing, said pump means being connected to the inlet end of said-inner tubing for discharging said withdrawn liquid through said inner tubing, outlet means being attached to the end of said inner tubing remote from said pump means for coupling said inner tubing to saidheat exchange system for supplying said heat exchange system with cooling liquid, in-

let means attached to said tank for returning the cooled liquid from saidheat exchange system back to said tank,

and outer tubing coupling means being attached to spaced portions of said outer tubing for connecting it in circuit with said refrigerating system whereby said refrigerant is caused to expand in said outer tubing to simultaneously pre-cooil the liquid stored in said tank around said outer tubing before it is pumped through said inner tubing and to sub-cool the liquid within said inner tubing before it is pumped to said heat exchange system.

2. A device as set forth in claim 1 wherein said outlet means comprises a multi-outlet manifold connected to said inner tubing, and eachou-tlet of said manifold having an individual, control valve.

3. A device as set forth in claim 1 wherein said inner 5. A device as set forth in claim 4 wherein said pump means is mounted under said tank, and said compressor and condenser are mounted under said tank.

6. A device as set forth in claim 5 wherein said expansion valve and the cold refrigerant piping are disposed within said tank.

7. A device as set forth in claim 4 wherein solenoid valve means are connected between the discharge line of said compressor and the inner tubing discharge line, and an adjustable indicating thermostat controlling said solenoid valve means for maintaining a preselected liquid References Cited by the Examiner UNITED STATES PATENTS Oman 62434 Dolison 6298 Dei-bel 62-396 Shepard 62399 X LLOYD L. KING, Prima'ry Examiner.

Claims (1)

1. A LIQUID CHILLING DEVICE FOR SUPPLYING A HEAT EXCHANGE SYSTEM WITH LIQUID COOLED BY A REFRIGERANT SYSTEM EMPLOYING EXPANDING REFRIGERANT COMPRISING A STORAGE TANK FOR HOLDING A RESERVE LIQUID TO BE CHILLED, PUMP MEANS CONNECTED TO SAID STORAGE TANK FOR WITHDRAWING LIQUID THEREFROM, COAXIAL TUBING IN SAID STORAGE TANK INCLUDING INNER TUBING AND OUTER TUBING, SAID PUMP MEANS BEING CONNECTED TO THE INLET END OF SAID INNER TUBING FOR DISCHARGING SAID WITHDRAWN LIQUID THROUGH SAID INNER TUBIN, OUTLET MEANS BEING ATTACHED TO THE END OF SAID INNER TUBING REMOTE FROM SAID PUMP MEANS FOR COUPLING SAID INNER TUBING TO SAID HEAT EXCHANGE SYSTEM FOR SUPPLYING SAID HEAT EXCHANGE SYSTEM WITH COOLING LIQUID, INLET MEANS ATTACHED TO SAID TANK FOR RETURNING THE COOLED LIQUID FROM SAID HEAT EXCHANGE SYSTEM BACK TO SAID TANK, AND OUTER TUBING COUPLING MEANS BEING ATTACHED TO SPACED

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