Patent ID: 7818971

Claim:
A CO 2 cooling and heating apparatus comprising: a first refrigerating cycle circuit comprising: a first refrigerant flow path; a first compressor in the first refrigerant flow path for pressurizing a CO 2 refrigerant to the supercritical region of CO 2 ; a condenser in the first refrigerant flow path downstream from the first compressor for condensing the pressurized refrigerant; a first intermediate cooler in the first refrigerant flow path downstream of the condenser for further cooling the condensed refrigerant; a first expansion device in the first refrigerant flow path downstream of the first intermediate cooler for further cooling and condensing the refrigerant to a pressure/temperature level of the CO 2 triple point or below to reduce the refrigerant to a mixture of solid CO 2 and CO 2 gas; an evaporator in the first refrigerant flow path downstream of the first expansion device for sublimating the solid CO 2 in the mixture; a second compressor in the first refrigerant flow path downstream of the evaporator for compressing the refrigerant, wherein the refrigerant compressed by the second compressor is introduced into the first compressor; and a second refrigerating cycle circuit comprising: a second refrigerant flow path including a first branch path branching off the first refrigerant flow path at a point between the condenser and the first intermediate cooler; a second expansion device in the second refrigerant flow path for further cooling and evaporating part of the refrigerant from the condenser; and the first intermediate cooler also in the second refrigerant flow path for further cooling the refrigerant in the first refrigerant flow path and for evaporating the refrigerant in the second refrigerant flow path by heat exchange, wherein the refrigerant passing through the second expansion device is introduced into the first intermediate cooler in the second refrigerant flow path, and wherein the refrigerant passing through the first intermediate cooler is introduced to the first refrigerant flow path between the first compressor and the second compressor so that the second refrigerating cycle circuit operates above the pressure/temperature level of the CO 2 triple point.