US2158716A - Refrigeration - Google Patents

Description

May 16, 1939. J, G. BERGDOLL REFRIGERATION Filed Dec. 19, 1953 than May 16, 1939 PATENT 'oFF1cE nnrarenm'rron John G. Bergdoll, York, Pa., assignor to York Ice Machin cry Corporation, York, Pa a rporation of Delaware Application December 19, 1933, Serial No. 103,141

7 Claims. (01. 62127) 7 valve I, of known commercial form. This ther- This invention relates to refrigeration, and particularly to means for supplying volatile refrigerant to a plurality of evaporators connected in parallel. v

In certain commercial installations it is desirable to connect a plurality of evaporators in parallel and feed them with refrigerant by means of a single expansion valve. The expansion valve may be manually controlled or it may be automatically controlled. For example, a commercial expansion valve controlled in response to the temperatures of the vapors leaving the evaporators may be used.

The reasons for using such a plurality of evaporators involve practical considerations concerned with manufacture and installation, and since they are not material to the question of invention here presented, are not discussed in detail.

Since the pressure on the refrigerant changes in passage through the expansion valve, a part of the refrigerant will vaporize upon passage through the valve and consequently the discharge from the expansion valve can be regarded as a mixture of liquid refrigerant and refrigerant vapor. In any case, and particularly in cases where the evaporators are located at different heights, there is a tendency for certain of the evaporators to receive undue proportions of the liquid refrigerant, whereas others receive undue proportions of the vaporized refrigerant, with the result that the refrigerative effects of the different evaporators are unequal. The prime purpose of the presentinvention is to insure that uniform proportions of liquid and vapor are de- 35 livered to each of the various evaporators.

A further object of the invention, useful where a thermally responsive expansion valve is used, is to insure control of the valve by the average temperature of vapor leaving all the connected evaporators.

A preferred embodiment of the inventionis illustrated in the accompanying drawing, but as various specifically difierent arrangements, within the scope of the invention, are possible, this 5 4% is to be regarded as exemplary and not limiting.

Fig. l is an elevation showing three evaporators connected in parallel to be fed by a. single expansion valve of the thermally controlled type.

Fig. 2 is a vertical axial section of a. distributor 5n constructed in accordance with thepresent invention.

Fig. 3 is a plan view thereof.

Fig. iis a view similar to Fig. 1 showing a distributor used with evaporators of difierent capaci ties.

'Fig. 5 is a view similar to Fig. i showing the modification.

Referring first to Fig. 1, G'represents the liquid line which leads from a receiver or other source v 600 feet per minute.

of liquid refrigerantto an automatic expansion mostatic valve includes a thermometric bulb 8 which contains a volatile liquid, so chosen that it will develop a suitable pressure at the desired temperature of the vaporous refrigerant leaving the evaporator. The pressure thus developed in the bulb 8 is transmitted through a tube 9 to the expansion valve land there acts upon a pressure motor mechanism, which is, as usual, connected to actuate the valve element of the expansion valve.

Leading from the expansion valve 1 is a pipe I l which receives a mixture of refrigerant liquid and vapor discharged from the valve 1. The pipe I l leads to the inlet connection 12 of a distributing fitting made upcf two parts, I3 and H, which are hermetically sealed together in any suitable manner.

In line with the entrance connection 12 is a nozzle IE to which the pipe i i delivers, the dimension of the nozzle being so chosen that it will discharge refrigerant at a velocity of the order of This nozzle discharges in line with the axis of a circular chamber 16 whose diameter preferably materially exceeds its axial dimension.

In the example illustrated, the jet discharged by the nozzle it impinges upon "a flat surface ll at right angles to said nozzle, and the efiect is to produce rotary turbulence in the chamber IS, the turbulent flow occurring in what may be described as a ring or torus in the o'utenportion of the chamber it. Since the ring-shaped turbulence thus induced, is symmetrical with reference to the nozzle it, the euect is to insure a uniform mixture of liquid and vapor in all portions of the chamber it.

Leag from the chamber it are a. plurality of discharge connections it, one for each evaporator to be fed. In the example illustrated there are three evaporators, and consequently three such connections. These connections are out of line with the jet discharging from the nozzle it and are symmetrically arranged with respect thereto.

Leading from the connections it are corresponding discharge pipes it, each of which leads to a. different evaporator, the evaporators being indicated generally by the numeral ft. The exact form of the evaporators is immaterial, but for illustrative-purposes there has been chosen a familiar type comprising zig-zag tubes 2f passing through and contacting with a series of spaced radiating plates, one of which, in the case of each evaporator, is indicated at 23. Each evaporator has a discharge connection 24 leading to a discharge manifold 25 which in turn is connected with the suction line 26.

In order to subject the thermometric bulb 8 to the average discharge temperature in the various 'tions.

evaporators, the bulb is mounted in contact with the suction line 26 close to its junction with manifold 25. It is common practice in this art to place the bulb inside the pipe, and there is nothing in the present invention to preclude such practice if preferred.

The function of the fitting l3, I4, is to insure the distribution of a uniformly proportioned mixture of liquid and vapor to a plurality of connected evaporators, and a number of factors can be coordinated to insure a satisfactory result. In the first place, the result is promoted if the connections l8 are all of approximately the same size and shape. It is important that the surface in the chamber l6, adjacent each connection Ill, be of similar character as to smoothness and finish. The arrangement shown, in which the fitting I3, I 4, is mounted with its axis vertical, is also important as minimizing the effect of gravity on the distribution of liquid. The simplest possible arrangement is secured when the connections l8 are all of the same size, the evaporators 2| are all of the same size, and the pipes 19 are all of the same size and as nearly as practicable of equal length.

Where the evaporators are necessarily of different sizes or where the pipes i9 are necessarily of substantially different lengths, a correction factor may be introduced by changing the bore of the pipe [9 or the size of the orifice 20 in the fitting H or connection i 8, or both. Fig. 4 shows the use of tubes of different sizes, with evaporators of difierent sizes and different loca- The large evaporator Zia is above the smaller evaporators 2 lb and 2 lo and the tube I941 is, therefore, made somewhat larger than the tubes Nb and I90. The tubes are proportioned to balance the distribution. In Fig. 5" an alternative arrangement is suggested in which the orifice 20b in the distributor head is smaller than the orifice 20a in the same distributor head, the size of the orifice being proportioned to the size of the evaporator to which it is connected, the connecting tubes all being of the same size. Precise rules for the proportioning of the pipe or orifice, cannot be given, but satisfactory results may readily be had by trial and error.

The important point is that the invention is not limited to the use of identical evaporators though identity in the size of the evaporators does simplify the attainment of the desired result.

When thesystem is in operation the expansion valve 1 discharges into the pipe II a mixture of liquid and vapor refrigerant, the rate of such delivery, being controlled in response to temperature of refrigerant leaving the manifold 25, by the operation of th'e thermometric bulb 8. The

,contracted orifice l5 insures high velocity discharge of the liquid and vapor into chamber l6, and the jet thus formed impinges on the fiat surface at the center of chamber l6 and induces a violent rotary turbulence at the point of subdivision of the off-flowing mixture, so that all of the connections I8 receive a mixture of uniform character, whether or not the quantities of mixture flowing through the various connections are equal. If the evaporators are all of the same capacity the quantities will be equal, but if the evaporators have different capacities the quantitles will be different. The invention can be used to attain either result, and the effect is to insure a condition in which no one evaporator receives an undue proportion of liquid as compared to vapor. Consequently, all the evaporators function emciently, and the regulatory effect of the bulb 8 is satisfactory for the evaporators considered as a group.

Broadly considered, the invention involves the interposition between a single expansion valve and a plurality of evaporators connected to be fed in parallel thereby, of means effective at the point of subdivision of the streams flowing from the expansion valve to the various evaporators to induce violent turbulence, and specifically to induce such turbulence as the result of fiow of the refrigerant itself. This idea is capable of embodiment in various specifically different forms, and while the form illustrated is preferred, because of its simplicity and demonstrated efficiency, the possibility of other embodiments is recognized, and the structure above described in detail is for purposes of illustration, and implies no limitations other than those expressed in the claims.

What is claimed is,

1. The method of insuring the supply of uniform mixtures of liquid and vaporous refrigerant from a single expansion device to a plurality of evaporators arranged in parallel, which comprises subdividing the stream of mixture delivered by such expansion device, and immediately in advance of such subdivision inducing, by the flow of the refrigerant itself, violent rotary turbulence in the flowing stream of refrigerant.

Means for distributing to a plurality of branch lines uniform mixtures of liquid and vapor delivered by an expansion device, comprising a chamber and a related supply nozzle arranged to induce turbulent flow in the chamber, said nozzle being fed by said expansion device and the chamber having a plurality of discharge passages leading therefrom out of line with the jet discharged by said nozzle and similarly arranged with reference to such turbulent flow.

3. The combination of an expansion valve; a plurality of evaporators adapted to be fed in parallel with refrigerant delivered by said expansion valve; and a branch fitting interposed between said expansion valve and said evaporators, said fitting having a high velocity injection nozzle connected with the discharge of the expansion valve, a chamber in which the jet discharged by the nozzle induces turbulent flow, and symmetrically arranged outlet passages leading from said chamber to respective evaporators.

4. The combination defined in claim 2, in which the jet discharged by the nozzle is directed vertically.

5. The combination defined in claim 3, in which the jet discharged by the nozzle is directed vertically.

6. The combination defined in' claim 3, in which the evaporators are of unequal refrigerative capacities and the outlet passages are of sizes proportioned to the capacities of the evaporators fed thereby.

7. An expansion mechanism for refrigeration evaporators, comprising an expansion valve, a distributor head, a plurality of outlets in said head leading to a plurality of evaporators, a plurality of orifices connecting with said outlets, a channel connecting said orifices with the output side of said valve, and means within said channel for spinning the gas and liquid during its travel therethrough to prevent their segregation. I

JOHN G. BERGDOLL.

Images