US2142520A

US2142520A - Thermocompressor

Info

Publication number: US2142520A
Authority: US
Inventors: John A Maclean
Original assignee: Ingersoll Rand Co
Current assignee: Ingersoll Rand Co
Priority date: 1935-08-15
Filing date: 1935-08-15
Publication date: 1939-01-03
Anticipated expiration: 1956-01-03

Description

J. M LEAN Jan. 3, 1939.

THERMOCOMPRES S OR Filed Aug. 15, 1955 :N yENToR v Jo/m AMacliearz Hi5 ATTORNEY.

Patented Jan. 3, 193? UNITED STATES THEBMQGOMP'BESSOR unclean. Hampton, N. 1., asalgnor Ingeraoll-Rand Company, Jersey City, N. J a

JohnA.

corporation of New Jersey Alipllcation Al 15, 1935, Serial No. 36, 71

2 Claims. (Cl. 23-111) My invention relates to improvements in theme-compressors, and particularly thermocompressors of the steam-jet booster type.

An object of the invention is to provide a steam-jet booster so constructed that the capacity and ratio of compression can be varied according to working conditions, by adjustment of the distance between the jet and the throat of the Venturi tube.

Another object is to construct a convergentdivergent passage or venturi out of simple ele-- ments.

These and other objects of the invention are set forth in the ensuing description and the novel features are pointed out in the appended claims. While I show and disclose herein a preferred embodiment of the invention, I may, nevertheless, vary the details of construction without departing from the principle of the invention or exceeding its spirit and scope.

0n the drawing the figure shows a steam-jet booster according to this invention, in longitudinal section.

The numeral I indicates a tubular ejector casing having an inlet 2 at one end for the admission of fluid to be displaced and compressed. In practice this ejector may be mounted upon a vessel called an evaporator in which a liquid refrigerant is cooled by converting it partly into vapor, which passes out of the evaporator and through the inlet opening 2 into the casing l. The end of the casing l adjacent the inlet 2 is made so that it is open when the casing is finished and at said end is a steam chest I connected to a steam supply pipe I. This end of the casing is closed by a mounting plate 5 which is between the casing and steam chest 3, both the plate andthe chest being held removably in place by any suitable means. The plate 5 supports a number of steam nozzles 6 which may be arranged in a circular row. When steam is discharged from the nozzles it creates a partial vacuum in the evaporator below the inlet 2 and draws the vapor out of the evaporator, impelling it through the easing l to the condenser (not shown) where both the steam and vapor are liquefied.

Within the casing is a regulating member I of varying cross section, being thickest near the opening 2 and of smallest diameter adjacent its opposite extremity. Amxed to the plate 5 is a guide 8 which projects into the member I and on which the member can slide when it is moved. At the delivery end the casing l is bolted to a spider 9, interposed between the casing and the discharge conduit leading to the condenser, and

at the center of the element I and enclosed within the casing is a hollow boss II, the end of which engages slidably with the member ill and it is amxed within this member to the movable extremity of a sylphon ii, the other end of which p is secured to the spider 9. All the moving parts are, therefore, enclosed in the casing and no seala ing devices are necessary to prevent leakage therearound.

The sylphon is a therrnally-responsive device connected to move the member 1 as a tempera-- ture aflecting the operation of the compressor varies. In the form shown, the sylphon is shielded from the fluid in the casing by a boss "I and receives an expansible liquid connected to be influenced by the temperature of the contents of a pipe I! in which is mounted a bulb ll connected by means of a piece of tubing IS with the sylphon I! through a passage It in one of the legs of the spider 9.

When the ejector is mounted upon the evaporator of a refrigerating device the conduit ll may be the'member whichcarries off from the evapo rator the refrigerant after it has been cooled an thus the-position of the member 1 will be varied according to the temperature of the chilled refrigerant flowing through the conduit IS.

The member I is of stream-line form being rounded at the end I! which engages the guide 8. Adjacent this end is a cylindrical section l8, beyond which the member 1 tapers as shown at I! to the shank H. The annular space or throat 2' around the section I! is of course unalterable in size. The external surface of the member I and the internal surface of the casing I defines the venturi into which the jets 8 discharge.

The sylphon I! as it expands and contracts will move the member I, causing it to slide on the guide 8 and causing the stem II at the other end to slide in the bearing of the projection Hi. When this member moves to the left the Venturi throat is moved closer to the jets which increases the ratio of compression capable of being developedv by the booster. Such a characteristic is in accordance with well known principles, and consequently the compressor can operate against a greater back pressure. When the member moves to the right the Venturi throat is moved away from the jets and the back pressure against which the compressor can work is decreased; Therefore, if the temperature of the cooled refrigerant in the conduit It should drop the member 1 will move away from the nomles 8 to cut down both porthat is forced through the casing I to the condenser, and when the temperature rises the regulator I will be moved in the opposite direction to increase the ratio of compression and to 7 permit more steam and vapor to the casing.

In the ordinary type of steam jet ejector with a relatively constant ratio of compression and vapor handling capacity there is a limited range of satisfactory operation. When operating in connection with an evaporator, at low loads, heat wthrough (vapor) may be removed at so great a rate as to result in freezing the refrigerant unless some method, such as by-passing, is resorted to. At high loads the pressure in the condenser may increase to a point where it "breaks back through the ejector and increases the pressure in the evaporator to a point where refrigeration ceases.

With a movable Venturi throat as described the satisfactory upper and lower limits of the range of the ejector are materially extended by control of the operating characteristics of the compressor. v

This mode of operation enables the ejector to regulate the action of the refrigerating device as required because when the load or demand for refrigerating effect is highest the temperature of the refrigerant in the conduit II and the back pressure in the condenser will be relatively high, and the fluid in the bulb I4, tube 'II and sylphon I2 will force the member] to the left. The steam jets then have a higher ratio of compression and capacity and can extract the maximum amount of vapor from the evaporator and force it through the casing. On the other hand when the load drops. the temperature of the refrigerant returning to the evaporator will be lower and the temperature of the refrigerant after being chilled in the evaporator will be correspondingly less. Likewise the back pressure in the casing I from the condenser is diminished. Hence the influence of the temperature of the contents of the flue I3 will be to enable the sylphon I2 to contract, resulting in a movement of the member I to the right. This action results in less vapor at a lower pressure being forced through the space 20 and therefore less is extracted from the evaporator.

Hence there is less cooling of the refrigerant in the evaporator so that a minimum temperature can be selected. The refrigerant never becomes cooler than this minimum temperature and danger of freezing is thus obviated.

The element I is so positioned with respect to the nozzles I that movement to the left can never have an obsructing or throttling effect, and because of the parallel walls ofthe casing I the Venturithroat is constant in area irrespective of movement to the right or left.

with the foregoing construction the capacity of the booster is always adjusted to meet the demands for refrigeration, reducing the amount of vapor when the load on the system drops and increasing the amount removed so as to extract a maximum amount of heat from the refrigerant in the evaporator when the load is full. The general design of the evacuatoris quite simple, as will be perceived, and it is certain in operation and not liable to get out of order.

I claim:

1. A compressor including a parallel walled cas. ing having an inlet at one end and one or more discharge nozzles therein adjacent the inlet, a regulator member in said casing, said member being elongated in shape and decreasing in diameter away from said nozzles, a guide on which one end of said member is slidably mounted, said member having a stem at the other end, a hollow projection mounted in the casing slidably engaging said stem, and means enclosed within the casing and subject to external conditions to adjust the position of said member.

2. A compressor including a cylindrical casing having an inlet and outlet and one or more discharge nozzles at one end, a venturi forming member in the casing decreasing in diameter toward said outlet, said member having a rounded end presented to said nozzles and having a portion of constant diameter adjacent said end and means for slidably mounting the end of said member adjacent said nozzles, said member havi'ng a guide stem at the opposite end, means carrying a hollow projection slidably receiving said stem, a sylphon in said projection connected to said stem, and a thermally responsive connection between said sylphon and the exterior of the casing.

JOHN A. MAOLEAN.