| 摘要 |
<p>Pulse width modulation is used to control the flow rate through a solenoid expansion valve in a refrigeration system using a dual evaporator, two-stage cycle. The refrigeration cycle includes a phase separator which receives two phase refrigerant from the low temperature evaporator and supplies liquid refrigerant to the pulse width modulated solenoid valve. A liquid level sensor is disposed in the phase separator, and a controller for controlling the duty cycle of the pulse width modulated solenoid valve is provided to receive input from the liquid level sensor. The liquid level sensor can be of the type which provides a continuously variable signal as a function of liquid level, or it can be a liquid level switch which controls valve duty cycle on the basis of whether the phase separator liquid level is above or below a set level. Alternatively, two liquid level switches can be provided.</p> |
