Cooling mechanism

A cooling mechanism for cooling a processing-assisting contributive liquid used in a processing apparatus, comprising:

• a controller;
• a compressor for compressing a CO2 coolant;
• a water-cooling gas cooler for cooling the CO2 coolant that has retained heat generated when compressed by the compressor;
• an internal heat exchanger for being supplied with the CO2 coolant that has been cooled by the water-cooling gas cooler;
• a vaporizer for vaporizing the CO2 coolant delivered from the internal heat exchanger, thereby generating heat of vaporization, and cooling the processing-assisting contributive liquid used in the processing apparatus;
• a first pathway interconnecting the compressor and the water-cooling gas cooler;
• a second pathway interconnecting the water-cooling gas cooler and the vaporizer;
• a third pathway interconnecting the vaporizer and the compressor;
• a fourth pathway having a water control valve for introducing industrial water into the water-cooling gas cooler;
• and
• a bypass pathway interconnecting a first joint joined to the first pathway and a second joint joined to the second pathway and having a variable bypass valve,
• wherein the internal heat exchanger is disposed across the second pathway and the third pathway such that the CO2 coolant delivered from the vaporizer deprives heat from the CO2 coolant delivered from the water-cooling gas cooler,
• the cooling mechanism further includes
• a variable expansion valve that is disposed on the second pathway between the internal heat exchanger and the second joint and regulates a flow rate of the CO2 coolant that has been cooled,
• a first pressure sensor that is disposed on either the second pathway or the third pathway between the variable expansion valve and the compressor and measures a pressure of the CO2 coolant,
• a second pressure sensor that is disposed on either the first pathway or the second pathway between the compressor and the variable expansion valve and measures the pressure of the CO2 coolant that has been compressed by the compressor,
• a first temperature sensor for measuring a temperature of the processing-assisting contributive liquid that flows out of the vaporizer,
• a second temperature sensor for measuring the temperature of the processing-assisting contributive liquid that flows into the vaporizer,
• a third temperature sensor for measuring a temperature of the industrial water flowing into the water-cooling gas cooler,
• a fourth temperature sensor for measuring the temperature of the CO2 coolant delivered from the compressor,
• a fifth temperature sensor for measuring the temperature of the CO2 coolant delivered from the water-cooling gas cooler,
• a sixth temperature sensor for measuring the temperature of the CO2 coolant delivered from the internal heat exchanger,
• a seventh temperature sensor for measuring the temperature of the CO2 coolant delivered from the vaporizer, which temperature is the same as the temperature of the CO2 coolant delivered from the variable expansion valve, and
• an eighth temperature sensor for measuring the temperature of the CO2 coolant delivered into the compressor, wherein:
• the controller includes a setting section for setting at least a first pressure value to be detected by the first pressure sensor, a second pressure value to be detected by the second pressure sensor, a first temperature to be detected by the first temperature sensor or a second temperature to be detected by the second temperature sensor, a fourth temperature to be detected by the fourth temperature sensor, a fifth temperature to be detected by the fifth temperature sensor, and an eighth temperature to be detected by the eighth temperature sensor, and
• the controller controls a degree of opening of the variable expansion valve and a rotational speed of the compressor to cause the CO2 coolant to follow a route that is defined by the set pressure values and temperatures in surrounding relation to a critical point specified by a critical temperature of 31.1° C. and a critical pressure of 7.38 Mpa, in order for a temperature value measured by the first temperature sensor or the second temperature sensor to reach the set temperature,
• wherein, when it is assumed that:
• a point A resides at an outlet of the compressor,
• a point B resides at an outlet of the water-cooling gas cooler,
• a point C resides at an outlet of the internal heat exchanger on the second pathway,
• a point D resides at an outlet of the variable expansion valve,
• a point E resides at an outlet of the vaporizer,
• a point F resides at an outlet of the internal heat exchanger on the third pathway,
• a temperature, a pressure, and an enthalpy at the point A are represented by TA, PA, and EA, respectively,
• a temperature, a pressure, and an enthalpy at the point B are represented by TB, PB, and EB, respectively,
• a temperature, a pressure, and an enthalpy at the point C are represented by TC, PC, and EC, respectively,
• a temperature, a pressure, and an enthalpy at the point D are represented by TD, PD, and ED, respectively,
• a temperature, a pressure, and an enthalpy at the point E are represented by TE, PE, and EE, respectively, and
• a temperature, a pressure, and an enthalpy at the point F are represented by TF, PF, and EF, respectively,
• the CO2 coolant delivered from the point F to the compressor is compressed by the compressor and reaches the point A in excess of the critical point, where the temperature changes from TF to TA, the pressure changes from PF to PA, and the enthalpy changes from EF to EA,
• the CO2 coolant delivered from the point A to the water-cooling gas cooler is cooled by the water-cooling gas cooler and reaches the point B where the temperature changes from TA to TB, the pressure remains unchanged (PA=PB), and the enthalpy changes from EA to EB, with a temperature difference between TA and TB and an enthalpy difference between EA and EB being discarded out of the cooling mechanism by the water-cooling gas cooler, the pressure PB and the temperature TB exceeding the critical point and the CO2 coolant being not liquified,
• the CO2 coolant delivered from the point B to the internal heat exchanger is deprived of heat by the CO2 coolant delivered from the vaporizer and reaches the point C where the temperature changes from TB to TC, the pressure remains unchanged (PB=PC), and the enthalpy changes from EB to EC, with the temperature TC being lower than the critical point and the CO2 coolant being partly liquified,
• the CO2 coolant delivered from the point C to the variable expansion valve is decompressed by the variable expansion valve and reaches the point D where the temperature changes from TC to TD, the pressure changes from PC to PD, and the enthalpy remains unchanged (EC=ED), with the CO2 coolant in a state where gas and liquid coexist,
• the CO2 coolant delivered from the point D to the vaporizer deprives the processing-assisting contributive liquid of energy in the vaporizer and reaches the point E where the temperature and the pressure remain unchanged (TD=TE and PD=PE), the enthalpy changes from ED to EE, the point E starts to go on a saturation vapor curve passing through the critical point, turning the CO2 coolant into gas,
• the CO2 coolant delivered from the point E to the internal heat exchanger deprives the CO2 coolant delivered from the point B to the internal heat exchanger of heat, with liquid that remains in the CO2 coolant turning into gas, and reaches the point F where the temperature changes from TE to TF, the pressure remains unchanged (PE=PF), and the enthalpy changes from EE to EF, and the CO2 coolant reaches the point A where an absolute value of a difference between EB and EC and an absolute value of a difference between EE and EF are equal to each other, and
• the controller controls the temperatures, the pressures, and the enthalpies to maximize a cooling efficiency (cooling ability/compression work)=(ED−EE)/(EF−EA).