US 5,195,331 AGranted

Method of using a thermal expansion valve device, evaporator and flow control means assembly and refrigerating machine

AssigneeBernard Zimmern

InventorsBernard Zimmern, Jean L Picouet

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Abstract

The expansion valve 103 of the refrigerating machine is controlled by the difference between the pressure in a bulb 104 containing a fixed amount of fluid and the pressure in the evaporator 2. The bulb is mounted in the discharge pipe 1 of the evaporator and is heated by a resistor. In the absence of droplets of liquid refrigerant in the flow through the discharge pipe, i.e when the refrigerant flow rate tends to become too low with respect to the cold demand, the resistor heats up the fluid in the bulb, the pressure in the bulb increases and moves the expansion valve to a more opened position. As soon as droplets hit the bulb in the discharge pipe, said droplets cool down the bulb despite the heating effect of the resistor and the expansion valve is moved to a more closed position. Thus, the flow rate control uses variations in heat transfer coefficients in the discharge pipe rather than superheat temperature in the discharge pipe. The evaporator may be small-sized because it does not have to produce superheat.

Claims5

Dependent claims

The method for controlling a refrigeration system having an evaporator for passing a refrigerant from an adjustable thermal expansion valve to a pipe downstream from the evaporator with reference to direction of refrigerant flow, the system being capable of operating to maintain the refrigerant in the evaporator within a pressure/temperature region in which a substantial percentage of refrigerant in said pipe is in a liquid phase and further including a bulb for controlling operation of the thermal expansion valve, the bulb having a heat conductive wall with opposite inner and outer surfaces and containing a fluid having a liquid phase at least partially filling the bulb, the operation of the expansion valve being dependent on a thermal balance between the bulb contained fluid and refrigerant outside of the bulb, and including means for heating the bulb contained fluid, the method comprising the steps of:

mounting the bulb with at least a portion of aid heat conductive wall extending within the pipe downstream from the evaporator and thereby enveloping at least a substantial portion of the bulb outer surface with refrigerant flow in the pipe;
exposing at least part of the opposite inner surface portion of said heat conductive wall to fluid in said bulb;
and energizing said heating means to direct a substantial portion of the heat thereof to the liquid phase of fluid contained in the bulb at least when the refrigerant flow in the discharge pipe contains a liquid phase.

Dependencies are inferred from the claim text.

Facts

Application: 07/690,335Filed 26 Apr 1991 · continuation
Priority: FR 88 162079 Dec 1988
Granted: 23 Mar 1993
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

F25B 41/335
With the valve member being actuated by the fluid pressure, e.g. by the pressure of the refrigerant: via diaphragms
F25B 2341/0681
Expansion valves combined with a sensor: the sensor is heated
F25B 2500/15
Problems to be solved: hunting, i.e. oscillation of controlled refrigeration variables reaching undesirable values
F25B 2600/21
Control issues: refrigerant outlet evaporator temperature