Air conditioning and refrigeration systems utilizing a cryogen

A method of operating a refrigeration system having cryogenic cooling means in a liquid state and heat exchanger means, for controlling the temperature of a conditioned space to a predetermined temperature range adjacent to a selected set point temperature via at least a cooling cycle, with the cooling cycle comprising the steps of:

• providing a desired evaporation vapor pressure value of the cryogen as a function of the selected set point temperature,
• controlling the evaporation pressure in the heat exchanger means as a function of the desired evaporation vapor pressure value,
• drawing air from the conditioned space,
• moving the air in heat exchange relation with the heat exchanger means,
• discharging conditioned air into the conditioned space,
• sensing the temperature of the discharged conditioned air, providing a minimum temperature value for the discharged conditioned air,
• and controlling the mass flow rate of liquid cryogen from the cryogenic cooling means to the heat exchanger means to prevent the temperature of the discharged conditioned air from falling below the minimum temperature value.

A refrigeration system having cryogenic cooling means in a liquid state and heat exchanger means, which controls the temperature of a conditioned space to a predetermined temperature range adjacent to a selected set point temperature via at least a cooling cycle, the improvement comprising:

• means providing a desired evaporation vapor pressure value of the cryogen as a function of the selected set point temperature,
• means controlling the evaporation pressure in the heat exchanger means as a function of the desired evaporation vapor pressure value,
• means providing a desired superheat value of the cryogen exiting the heat exchanger means as a function of the selected set point temperature,
• and means controlling the mass flow rate of liquid cryogen from the cryogenic cooling means to the heat exchanger means as a function of the desired superheat value.

A refrigeration system having cryogenic cooling means in a liquid state and heat exchanger means, which controls the temperature of a conditioned space to a predetermined temperature range adjacent to a selected set point temperature via at least a cooling cycle, the improvement comprising:

• means providing a desired evaporation vapor pressure value of the cryogen as a function of the selected set point temperature,
• means controlling the evaporation pressure in the heat exchanger means as a function of the desired evaporation vapor pressure value,
• means for drawing air from the conditioned space, moving the air in heat exchange relation with the heat exchanger means, and discharging conditioned air into the conditioned space,
• means sensing the temperature of the discharged conditioned air,
• means providing a minimum temperature value for the discharged conditioned air,
• and means controlling the mass flow rate of liquid cryogen from the cryogenic cooling means to the heat exchanger means to prevent the temperature of the discharged conditioned air from falling below the minimum temperature value.