US2158792A - Header feed evaporator - Google Patents

Description

y 16, 1939- F. R. ERBACH HEADER FEED EVAPORATOR Filed Dec. 7, 1934 2 Sheets-Sheet 1 May 16, 1939. F. R. ERBACH HEADER FEED EVAPORAI'OR Filed Dec. 7, 1934 2 Sheets-Sheet 2 Patented May 16, 1939 UNITED STATES PATENT OFFICE 2,158,792 HEADER FEED EVAPORATOR Application December '7, 1934, Serial No. 756,470

8 Claims.

The invention relates to refrigerating apparatus and has reference more particularly to a header feed for supplying liquid refrigerant to plurality of evaporating coils.

When the supply of refrigerant to all the coils of a refrigerating system is substantially equal the refrigeration produced by each is the same, and therefore all the coils should return gas to the suction line of the system, whereas, in an unbalanced distribution some of the coils may return gas and some unevaporated liquid refrigerant. Therefore an object of theinvention is a to provide means .for uniformly distributing a supply of liquid refrigerant to a pluralityof evaporating coils of a refrigerating system so that the refrigerant delivered to each coil over a period of time will be substantially equal.

It is desirable to accomplish the above result with the use of a single liquid refrigerant valve on the evaporator coils of a refrigerating system. The invention has for an object to secure good distribution of the refrigerant by feeding the refrigerant to a header having outlets for each coil and by restricting the flow of refrigerant from these header outlets so as to maintain a sufliciently high pressure in the header to prevent evaporation of the refrigerant in the header. This is necessary to prevent the partial feeding of gas through the header orifices which would be the case if the header pressure were low enough to permit evaporation of the incoming refrigerant. The uniformity of refrigerant distribution from the various orifice outlets of the liquid feed header can be still further improved by pre-cooling the liquid refrigerant admitted to the header. Therefore, another object of the invention is to precool the liquid delivered to the header by providing a heat interchanger between the liquid refrigerant supply and the suction line leaving the evaporator coils. With pre-cooled liquid in the header a very wide range in header pressure is possible under varying operating conditions without interfering with the uniformity of refrigerant distribution.

Another object of the invention is to provide an adjustable orifice so that the size of the same can be varied at will. An adjustable orifice opening is desirable since the opening leading to each coil is dependent upon the amount of tube and fin surface supplied by the feed of each orifice. After definite determination of the proper orifice size for a given size unit the adjustable feature may be eliminated. Also the invention contemplates the provision of a fixed orifice which can, however, be readily cleaned.

With these and various other objects in view the invention may consist of certain novel features of construction and operation as will be more fully described and particularly pointed out in the specification, drawings and claims appended hereto.

a In the drawings which illustrate an embodiment of the invention and wherein like reference characters are used to designate like .parts Figure l is a plan view showing a plurality of evaporating coils equipped with the header feed of the invention and which are supplied with liquid refrigerant'from a special type of expansion valve;

Figure 2 is a front elevational view of the structure shown in Figure 1;

Figure 3 is a sectional view taken longitudinally through the header showing the orifices leading to the evaporating coils? Figure 4 is a sectional view through the header taken on line 4-4 of Figure 3; ,c

Figure 5 is-a perspective view showing a plurality of evaporating coils equipped with a modified construction of header feed having adjusting needles. for varying the size of the orifices leading to the coils Figure 6 is a sectional view along line 1-1 of Figure 6 showing the construction of the adjusting needles;

Figure 7 is an elevational View with the side wall broken away showing the header of the invention applied to a refrigerating system for cooling water, and

Figure 8 is a plan view,parts'being shown in section, of an expansion valve for supplying liquid refrigerant to the present header.

Referring to the drawings, particularly Figures 1, 2 and 3, a section of a refrigerating system is shown including a supply pipe l0 for delivering liquid refrigerant to the expansion valve l2 of any conventional type and which in turn delivers the liquid through pipe l3 to header HI, the said pipe connecting with a valve and header respectively. The header comprises a cylindrical member closed at one end and connecting with the liquid supply pipe l3 and with a plurality of evaporating coils forming an enclosure for the ends of said coils.

In Figure 1 the evaporating coils are shown equipped with fins II; which are disposed within the frame I! supporting the evaporating coils and through which is passed the medium to be cooled, for example, air, so that the same is brought into contact withthe fins and the coils. The ends of certain tubes are connected by armate sections of pipe I8 to provide a continuous length of tube forming a coil which finally joins with the suction line I9. Each evaporating coil is provided with a nipple 23, Figure 4, having a reduced portion fitting within an opening in the header I4 by which the inlet end of the coil is joined to the header having a sealing fit therewith. The nipple has a bore extending therethrough providing a small orifice 24 located within the header and which therefore forms the inlet to the evaporating coil, the liquid refrigerant from the header being delivered from the orifice to the coil. In the embodiment shown the orifice is provided with a wire 25 which extends outside of the header and is preferably soldered thereto but may be otherwise secured in a manner that will seal the header. This arrangement is not adjustable to vary the size of the orifice but the wire can be removed to clean the orifice of foreign matter.

The liquid supply pipe I0 is provided with a coiled section located within a heat exchanger 20. The exchanger has connection at its respective ends with the suction line 2| leading from the header I9. The gas flowing through the return 2| is at a relatively low temperature compared with the liquid refrigerant flowing through the supply pipe I0. By means of the heat exchanger considerable heat is removed from the liquid refrigerant and as a result the same is delivered to the expansion valve I2 and the header at a much lower temperature than would otherwise be the case. In fact, the liquid refrigerant is cooled to very nearly evaporator temperature.

The liquid refrigerant from supply pipe I0 passes through the expansion valve I2 into pipe I3 which delivers the same to the header l4. By reason of the small orifices 24 forming the inlet to the evaporating coils the cool liquid refrigerant in the header is maintained at a high pressure and therefore evaporation of the same within the header is prevented. Evaporation of warm refrigerant causes flash gas within the header which if allowed to generate would tend to monopolize one or more of the orifices, preventing the passage of liquid refrigerant to the respective evaporating coils. By maintaining a high pressure on the cool refrigerant within the header the generation of flash gas is prevented until after the liquid has been delivered to the evaporating coils. In the apparatus shown in the drawings the expansion valve I2 is provided with a diaphragm 29 which controls the movement of the valve and thus the quantity of liquid refrigerant delivered to the header. The cham-- her on the underside of the diaphragm is connected by tube 26 with the suction line 2| and thus the pressure on the underside of the diaphragm is equalized with the pressure of the evaporated refrigerant being returned to the compressor. The space above the diaphragm has connection with a thermostat bulb 21 through tube 28 so that the diaphragm has movement proportionately to variations in temperature of the thermostat bulb. It will therefore be understood that the operation of the valve is responsive to the temperature of the suction line as modified by the pressure existing in said suction line.

It is not necessary that the header of the invention be disposed horizontally. In Figure 5 a vertical header H4 is shown having a connection with pipe II3 which supplies the same with liquid refrigerant. The header connects with the inlet ends of the evaporating coils H5 by means of a. nipple I23 in a manner identical with that shown in Figure 4.

In this modification, however, the orifice I24, Figure 6, is flared at its end for accommodating the pointed end of the needle I29 passing through and extending outwardly of the bushing I30. The projecting end of the needle has threaded engagement with the threaded nut I3I which is threaded into a recess in the bushing to retain packing I32 around this portion of the needle. The bushing in turn has suitably threaded thereto the cap or housing I33 which encloses the projecting end of the needle, Before adjustment of the needle can be effected the housing must be removed. With the addition of adjusting means for the orifices such as described more or less refrigerant can be supplied to a selected evaporating coil to vary the refrigerant produced by that coil, while the pressure within the header can be maintained sufiiciently high to prevent generation of fiash gas.

The header feed of-the invention distributes the liquid refrigerant to all the coils uniformly and the refrigeration produced by each coil is substantially equal so that all the coils return gas to the suction line. Therefore, the warm air to be cooled which may be admitted to the bottom of frame I! and expelled at the top thereof, Figure 2, is subjected to a network of fins and evaporating coils, each of which is doing its share of the refrigeration so that none of the air tends to bypass sections of the coils which generally occurs where the refrigeration produced by certain of the coils is greater than that produced by others. The advantage of admitting the warm air to the bottom of frame I1 resides in the fact that the air initially comes into contact with the outlet end of the evaporating coils and functions to evaporate any liquid refrigerant which might remain in the. coils. The air then passes upwardly in a direction counter to the flow of the liquid refrigerant in the coils so that as the air leaves the frame at the' top it passes over that section of the evaporating coils containing liquid refrigerant and which are consequently the coldest, thereby reducing the temperature of the air to the lowest possible point.

In Figure 7 the header of the invention is shown in connection with a refrigerating system including a plurality of evaporating coils 34 supported -by a frame 35. In this modification the fins have been omitted from the coils and the arrangement is designed for cooling water which is sprayed over the coils by the sprayers 36. The refrigerating system of Figure 5, having the vertical type header I I4, may be employed in the cooling of air, in which case the coils are preferably provided with fins I I6, and the air may be delivered at the front, in which case it will leave the frame I I! at the rear thereof.

The improved header feed of the invention will supply a plurality of coils with liquid refrigerant in equal amounts, although the header connects with the compressor of the system through a single expansion valve. The small orifice openings maintain the necessary high pressure in the header to prevent evaporation and generation of flash gas therein. By pre-cooling the liquid refrigerant through the use of a heat interchanger in the suction line the liquid is cooled to a temperature lower than the boiling point of the liquid in the header and therefore greater uniformity in th distribution of liquid to the various coils is secured and a wider range between the condensing and evaporating pressure is possible. The pressure in the header may be described as intermediate since it is below the pressure on the discharge side of the compressor but above that existing in the evaporating coils. The expansion valve automatically supplies the header with the required amount of liquid refrigerant to take care of the load on the evaporating coils and which therefore maintains the proper pressure in the header. The valve has operation responsive to the temperature of the suction line. However, this temperature control is modified by the pressure existing in the suction line as the underside of the diaphragm of the expansion valve is subjected to this pressure. By providing an adjusting needle for varying the size of the orifice openings a more flexible installation is secured since the orifice opening is dependent upon the amount of tube and fin surface of the coil fed by said orifice. When accurate determination of this factor has been made the adjustment of the orifice need not be varied and subsequent installation can be supplied with an orifice such as shown in Figure 4 which is not adjustable but which can be cleaned of foreign matter by removing the wire.

The invention is not to be limited to or by details of construction of the particular embodiment thereof illustrated by the drawings, as various other forms of the device will of course be apparent to those skilled in the art without departing from the spirit of the invention or the scope of the claims.

What is claimed is:

1. In a refrigerating system, a plurality of evaporating coils, each coil having a small orifice forming the inlet for said coil, a header joining the inlet end of each coil and enclosing the orifices thereof, means supplying liquid refrigerant to said header, and a length of wire for each coil fixed to the exterior of the header, each wire extending within the header and having association with the orifice of its respective coil.

.2. Means for uniformly distributing liquid refrigerant to a plurality of evaporating coils, com- I prising a header connecting with and enclosing the inlet end of each of said coils, the inlet end of each of said coils comprising a small orifice, an expansion valve having means supplying said valve with liquid refrigerant, and a connection on the out-put side of said valve joining with the header, whereby liquid refrigerant is supplied to each coil through the orifice forming the inlet thereof, and means extending through the wall of said header and operable from the exterior for cleaning each of said orifices respectively.

3. In a refrigerating system, the combination with an evaporator, of a header enclosing the inlet end of a plurality of evaporating coils, each coil having a small orifice within the header forming the inlet through which liquid refriger- Y ant is delivered to the coil, an expansion valve having a connection on the out-put side thereof joining with the header, whereby liquid refrigerant in the header is maintained at a pressure between the evaporating and condensing pressures, means supplying said expansion valve with liquid refrigerant, and means utilizing the cooled refrigerant gas flowing through the suction line of the evaporator for cooling the liquid refrigerant prior to supplying the same to the expansion valve.

4. In a refrigerating system, the combination with an evaporator, of a header enclosing the inlet end of a plurality of evaporating coils, each coil having a small orifice within the header forming the inlet through which liquid refrigerant is delivered to the coil, an expansion valve having a connection on the out-put side thereof joining with the header, whereby liquid refrigerant in the header is maintained at a pressure between the evaporating and condensing pressures, means supplying said expansion valve with liquid refrigerant, and means utilizing the-cooled refrigerant gas flowing through the suction line of the evaporator for cooling the liquid refrigerant prior to supplying the same to the expansion valve, said last mentioned means precooling the liquid refrigerant to a temperature lower than the boiling point of the refrigerant in the header.

5. In a refrigerating system, the combination with an evaporator, of a header enclosing the inlet end of a plurality of evaporating coils, each coil having a small orifice within the header forming the inlet end thereof through which liquid refrigerant is supplied to the coil, an expansion valve having a connection on the output side thereof joining with the header, means supplying the expansion valve with liquid refrigerant, and means utilizingthe cool refrigerant gas fiowing through the suction line of the evaporator for cooling the liquid refrigerant prior to supplying the same to the expansion valve, whereby said small orifices maintain the liquid refrigerant within the header at a relatively high pressure which in conjunction with the precooling of the refrigerant prevents evaporation within the header.

6. In a refrigerating system, the combination with an evaporator, of a header enclosing the inlet end of a plurality of evaporating coils, each coil having a small orifice within the header forming the inlet end thereof through which liquid refrigerant is supplied to the coil, an expansion valve having a connection on the out-put side thereof joining with said header, means supplying said valve with liquid refrigerant, whereby the refrigerant in the header is maintained at a pressure intermediate the evaporating and condensing pressures, a diaphragm for controlling the operation of 'said valve, said diaphragm having movement proportionate to variations in the temperature of the refrigerant gas leaving the evaporator as modified by the pressure of said refrigerant gas, and means utilizing the cool refrigerant gas flowing through the suction line for a cooling the liquid refrigerant prior to supplying the same to the expansion valve.

7. In a refrigerating system, the combination with an evaporator, of a header enclosing the inlet end of a plurality of evaporating coils, each coil having a small orifice within the header forming the inlet end thereof through which liquid refrigerant is supplied to the coil, an expansion valve having a connection on the out-put side thereof joining with said header, means supplying said valve with liquid refrigerant, whereby the refrigerant in the header is maintained at a pressure intermediate the evaporating and condensing pressures, a diaphragm for controlling the operation of said valve, a thermostat exposed to the refrigerant gas leaving said evaporator, means acting on one side of said diaphragm for moving the same proportionate to variations in said thermostat, means equalizing the pressure on the underside of said diaphragm with that existing in the suction line of the evaporator, and means utilizing the cool refrigerant gas flowing through the suction line for cooling the of the suction line of the refrigerating system and utilizing the cool refrigerant gas flowing through the same for cooling the liquid refrigerant in said first mentioned means prior to supplying the same to the valve, whereby said flow 5 resistant passages maintain the liquid refrigerant within the header at a relatively high pressure which in conjunction with the precooling 0f the refrigerant prevents evaporation within the header.

FRED R. ERBACH.

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