US2705404A - Cooling arrangement for condenser of refrigerating system - Google Patents

Description

April 5, 1955 H. s. MALUTICH 2,705,404 COOLING ARRANGEMENT FOR CONDENSER OF REFRIGERATING SYSTEM Filed May 8, 1952 COMPRESSOR Inventor": Harry S- Malutich,

His Attofneg- United States Patent COOLING ARRANGEMENT FOR CONDENSER OF REFRIGERATING SYSTEM Harry S. Malutich, Erie, Pa., assignor to General Electric Company, a corporation of New York Application May 8, 1952, Serial No. 286,780

6 Claims. (Cl. 62-3) My invention relates to refrigerating systems and more particularly to cooling arrangements for the condenser of a refrigerating system.

Many present day refrigerating systems include a condenser and an evaporator connected by a restrictor, or capillary, tube. Refrigerating systems are, of course, subjected to varying loads and to different ambient conditions. As a result, in some cases, the condenser may tend to run at too high a temperature. As the condenser temperature rises with the resulting increase in the high side pressure, the capillary tube tends to blow gaseous refrigerant through to the evaporator, thereby causing inefficiency. In the converse situation, when the condenser temperature decreases so that the condenser is running too cool, there is a tendency to collect liquid refrigerant in the condenser, thus starving the evaporator. In accordance with my invention, a fan-cooled condenser is provided and the operation of the fan thereof is varied so as to maintain the condenser temperature within a desirable range to obtain optimum efficiency and avoid starving of the evaporator.

It is an object of my invention to provide an improved arrangement for controlling the cooling of a fan-cooled condenser of a refrigerating system.

It is. another object of my invention to provide an improved arrangement for varying the cooling of a fancooled condenser in response to the temperature thereof.

It is a further object of my invention to provide, in connection with a fan-cooled condenser, an improved arrangement for varying the speed of the fan in response to the temperature of the condenser.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention, reference may be had to the accompanying drawing, the single figure of which discloses schematically one embodiment of my invention.

Referring to the drawing, there is shown a refrigerating system which includes a refrigerating unit 1, a condenser 2 and an evaporator 3 connected in a series refrigerant circuit. Vaporized refrigerant is returned to the refrigerating unit 1 through a suction line 4 and compressed refrigerant is supplied from the refrigerating unit to the condenser through a discharge line 5. The condenser 2 is connected to the evaporator by a reestrictor tube 6, known as a capillary tube, for metering refrigerant from the condenser to the evaporator.

The condenser 2 is a fan-cooled condenser. That is, in order for the condenser 2 to operate satisfactorily in the refrigerating system for removing heat from the compressed refrigerant and facilitating the condensation of compressed gaseous refrigerant, it is necessary that air be forced or blown across it by a fan 7. This arrangement enables me to control the operation of the fancooled condenser in the refrigerating system by controlling the operation of the fan thereof.

The fan 7 is driven by an electric motor 8 to which power is supplied from power lines 9 through lines 10 and 11. The electric motor 8 may be any one of various types suitable for driving the fan 7 and capable of having its speed varied by a resistor in series therewith. For example, the electric motor 8 may be a single phase induction motor including a starting winding 12 and a running winding 13. In accordance with conventional practice, a suitably actuated switch 14 is provided for opening the circuit of the starting winding as the motor comes up to speed. In this form of invention a resistor 15 is connected in series with the running winding of the induction motor 8. Variation in the resistance value of the resistor 15 can thereby be used for varying the speed of the motor 8.

In order to effect automatic variation in the speed of the motor 8 for varying the cooling of the condenser 2, the resistor 15 is formed of a material having a negative temperature coeflicient of resistance, that is, a characteristic such that the resistance decreases as the temperature of the resistor increases. By Way of example, a thermistor, which has the characteristic of decreasing in resistance with increase in temperature, may be employed for this purpose. The resistor 15 is disposed in heat exchange relationship with the inlet end 16 of the condenser. This may be accomplished in any suitable manner, for example, by clamping the resistor against the tube 16 to insure good heat exchange relationship.

With the arrangement described above, it can be seen that normally the fan 7 will operate at a predetermined speed for maintaining the temperature of the condenser within a predetermined range, however, should the temperature of the condenser, and specifically of the inlet end 16 of the condenser, increase above the predetermined range, the increase in temperatuer results in a reduction in the resistance of the resistor 15 and a corresponding increase in the voltage and current applied to the electric motor 8, and specifically to the running winding 13 thereof. This results in an increase in the speed of the motor 8 and therefore an increase in the amount of air supplied by the fan 7 across the condenser 2. Greater cooling of the condenser is thereby effected and the temperature thereof brought down within the desired range.

Conversely, should conditions be such that the temperature of the condenser, and specifically of the inlet tube 16 thereof, goes below the predetermined range, there is a resultant increase in the resistance of the resistor 15 and a corresponding decrease in the normal speed of the motor 8. The amount of air normally supplied by the fan 7 is accordingly reduced and hence the cooling effect on the condenser 2 is reduced, permitting the temperature of the condenser 2 to rise to the predetermined desirable range.

As mentioned above, while the electric motor 8 has been described in the particular embodiment as a single phase alternating current induction motor, it will be apparent that any other type of motor having characteristics such that variation of the resistance of a resistor connected in series therewith is effective to vary the speed of the motor could be employed. For example, a shunt wound or series wound motor could be used.

While I have shown and described a specific embodiment of my invention, I do not desire my invention to be limited to the particular construction shown and described and I intend, by the appended claims, to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a refrigerating system a compressor, a fan-cooled condenser and an evaporator connected in a series refrigerant circuit, a restrictor tube connecting the condenser and the evaporator, a motor normally driving the fan of said condenser for maintaining said condenser within a predetermined temperature range, an electrical circuit for supplying power to said motor, and a resistor in series with said motor for varying the speed thereof, said resistor having a negative temperature coetficient of resistance, said resistor being disposed in heat exchange relationship with said condenser whereby any increase or decrease in temperature of said condenser from said predetermined range decreases or increases, respectively, said resistance to increase or decrease, respectively, the speed of said motor and the cooling of said condenser.

2. In a refrigerating system a compressor, a fan-cooled condenser and an evaporator connected in a series refrigerating circuit, a restrictor tube connecting the condenser and the evaporator, a motor normally driving the fan of said condenser for maintaining said condenser within a predetermined temperature range, an electrical circuit for supplying power to said motor, and a resistor in series with said motor for varying the speed thereof, said resistor having a negative temperature coefficient of resistance, said resistor being disposed in heat exchange relationship with the inlet end of said condenser whereby any increase or decrease in temperature of said inlet end of said condenser from said predetermined range decreases or increases, respectively, said resistance to increase or decrease, respectively, the speed of said motor and the cooling of said condenser.

3. In a refrigerating system a compressor, a fan-cooled condenser and an evaporator connected in a series refrigcrating circuit, a restrictor tube connecting the condenser and the evaporator, a motor normally driving the fan of said condenser for maintaining said condenser within a predetermined temperature range, an electrical circuit for supplying power to said motor, and a thermistor in series with said motor for varying the speed thereof, said thermistor being disposed in heat exchange relationship with said condenser whereby any increase or decrease in temperature of said condenser from said predetermined range decreases or increases, respectively, the resistance of said thermistor to increase or decrease, respectively, the speed of said motor and the cooling of said condenser.

4. In a refrigerating system a compressor, a fan-cooled condenser and an evaporator connected in a series refrigerating circuit, a restrictor tube connecting the condenser and the evaporator, an induction motor normally driving the fan of said condenser for maintaining said-condenser within a predetermined temperature range, said motor having a starting winding and a running winding, an electrical circuit for supplying power to said motor, and a resistor in series with said running winding of said motor for varying the speed thereof, said resistor having a negative temperature coefficient of resistance, said resistor being disposed in heat exchange relationship with said condenser whereby any increase or decrease in temperature of said condenser from said predetermined range decreases or increases, respectively, said resistance to increase or decrease, respectively, the speed of said motor and the cooling of said condenser.

5. In a refrigerating system a compressor, a fan-cooled condenser and an evaporator connected in a series refrigerating circuit, a restrictor tube connecting the condenser and the evaporator, an induction motor normally driving the fan of said condenser for maintaining said condenser within a predetermined temperature range, said motor having a starting winding and a running winding, an electrical circuit for supplying power to said motor, and a resistor in series with said running winding of said motor for varying the speed thereof, said resistor having a negative temperature coefiicient of resistance, said resistor being disposed in heat exchange relationship with the inlet end of said condenser whereby any increase or decrease in temperature of said inlet end of said condenser from said predetermined range decreases or increases, respectively, said resistance to increase or decrease, respectively, the speed of said motor and the cooling of said condenser.

6. In a refrigerating system a compressor, a fan-cooled condenser and an evaporator connected in a series refrigcrating circuit, a restrictor tube connecting the condenser and the evaporator, an induction motor normally driving the fan of said condenser for maintaining said condenser within a predetermined temperature range, said motor having a starting winding and a running winding, an electrical circuit for supplying power to said motor, and a thermistor in series with said running winding of said motor for varying the speed thereof, said thermistor being disposed in heat exchange relationship with said condenser whereby any increase or decrease in temperature of said condenser from said predetermined range decreases or increases, respectively, the resistance of said thermistor to increase or decrease, respectively, the speed of said motor and the cooling of said condenser.

References Cited in the file of this patent UNITED STATES PATENTS 1,276,589 Steinmetz Aug. 20, 1918 1,769,119 Davenport July 1, 1930 1,779,116 Davenport Oct. 21, 1930 1,886,607 Van Deventer Nov. 8, 1932 1,919,743 Peters July 25, 1933 2,124,981 Krachowizer July 26, 1938 2,128,090 Hintze Aug. 23, 1938 2,194,372 Werner Mar. 19, 1940

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