Apparatus for measuring refrigerant flow rate in refrigeration cycle

In a refrigeration cycle including a liquid tank and having an expansion valve for causing an adiabatic expansion of a refrigerant, a refrigerant flow rate measuring apparatus comprising:

• a high-pressure side pressure detecting means for detecting a refrigerant pressure at an upstream side of said expansion valve;
• a low-pressure side pressure detecting means for detecting the refrigerant pressure at a downstream side of said expansion valve;
• an expansion valve opening degree detecting means for detecting a degree of opening of said expansion valves;
• and a calculating means for calculating a pressure differential between said high and low pressure side pressure detecting means and for calculating a flow rate of refrigerant passing through said expansion valve from a product of a square root of the pressure differential and an output of said expansion valve opening degree detecting means;
• and
• wherein said high-pressure side pressure detecting means includes a temperature detecting means for detecting a refrigerant temperature in a gas phase portion of a liquid tank, and a temperature-pressure converting means for converting an output of said temperature detecting means into pressure in accordance with a predetermined saturation characteristic of said refrigerant.

In a refrigeration cycle including an evaporator and having an expansion valve for causing an adiabatic expansion of a refrigerant, a refrigerant flow rate measuring apparatus comprising:

• a high-pressure side pressure detecting means for detecting a refrigerant pressure at an upstream side of said expansion valve;
• a low-pressure side pressure detecting means for detecting the refrigerant pressure at a downstream side of said expansion valve;
• an expansion valve opening degree detecting means for detecting a degree of opening of said expansion valves;
• and a calculating means for calculating a pressure differential between said high and low pressure side pressure detecting means and for calculating a flow rate of refrigerant passing through said expansion valve from a product of a square root of the pressure differential and an output of said expansion valve opening degree detecting means;
• and
• wherein said low-pressure side pressure detecting means includes a temperature detecting means for detecting a refrigerant temperature in a portion of the refrigeration cycle between an expansion valve outlet and an inlet of an evaporator, and a temperature-pressure converting means for an output of said temperature detecting means into pressure in accordance with a predetermined saturation characteristic of said refrigerant.

A refrigerant flow rate measuring apparatus in a refrigeration cycle the refrigeration cycle including a compressor, a condenser, a liquid tank, an ON-OFF expansion valve, and an evaporator, all being connected in series, said refrigerant flow rate measuring apparatus comprising:

• calculating means for calculating ON-OFF duty of said expansion valve in accordance with a state of operation of said refrigeration cycle;
• electric actuating means for actuating said expansion valve in accordance with an output from said ON-OFF duty calculating means;
• high-pressure side pressure detecting means for detecting refrigerant pressure at an upstream side of said expansion valve;
• low-pressure side pressure detecting means for detecting refrigerant pressure at a downstream side of said expansion valve;
• and refrigerant flow rate calculating means for calculating a pressure differential between the high- and low-pressure sides detecting means and calculating a flow rate of said refrigerant passing through said expansion valve from a produce of a square root of said pressure differential and a substantial opening area of said expansion valve calculating from an output of said ON-OFF duty calculating means.