In this paper, a carbon dioxide trans-critical refrigerating system which is different from a conventional subcritical refrigerating cycle was studied. The trans-critical carbon dioxide refrigerating systems are based on the Gustav Lorntzen cycle. Emphasis was focused on how to determine the optimal discharge pressure of compressor in CO2 trans-critical cycle. The factors related with the optimal discharge pressure were analyzed. A formula was developed based on cycle simulation, which could be used to predict the optimal discharge pressure of a basic CO2 trans-critical cycle. After further studies on CO2 trans-critical cycles with a regenerator or expander, two more formulas were also developed. These formulas could provide an access to improve the COP of CO2 trans-critical cycle.

In this paper, a carbon dioxide trans-critical refrigerating system which is different from a conventional subcritical refrigerating cycle was studied. The trans-critical carbon dioxide refrigerating systems are based on the Gustav Lorntzen cycle. Emphasis was focused on how to determine the optimal discharge pressure of compressor in CO2 trans-critical cycle. The factors related with the optimal discharge pressure were analyzed. A formula was developed based on cycle simulation, which could be used to predict the optimal discharge pressure of a basic CO2 trans-critical cycle. After further studies on CO2 trans-critical cycles with a regenerator or expander, two more formulas were also developed. These formulas could provide an access to improve the COP of CO2 trans-critical cycle.

In this paper, a carbon dioxide trans-critical refrigerating system which is different from a conventional subcritical refrigerating cycle was studied. The trans-critical carbon dioxide refrigerating systems are based on the Gustav Lorntzen cycle. Emphasis was focused on how to determine the optimal discharge pressure of compressor in CO2 trans-critical cycle. The factors related with the optimal discharge pressure were analyzed. A formula was developed based on cycle simulation, which could be used to predict the optimal discharge pressure of a basic CO2 trans-critical cycle. After further studies on CO2 trans-critical cycles with a regenerator or expander, two more formulas were also developed. These formulas could provide an access to improve the COP of CO2 trans-critical cycle.

Lower extremity deep vein thrombosis (DVT) is one of the main complications in patients with traumatic fractures, and for severe patients, the DVT can even affect arterial blood supply, resulting in insufficient limb blood supply. If the thrombus breaks off, pulmonary embolism may occur, with a high mortality. The treatment and rehabilitation strategies of thrombosis in patients with lower extremity fractures have its particularity. DVT in traumatic fractures patients has attracted extensive attention and been largely studied, and the measures for prevention and treatment of DVT are constantly developing. In recent years, a series of thrombosis prevention and treatment guidelines have been updated at home and abroad, but there are still many doubts about the prevention and treatment of DVT in patients with different traumatic fractures. Accordingly, on the basis of summarizing the latest evidence-based medical evidence at home and abroad and the clinical experience of the majority of experts, the authors summarize the clinical treatment and prevention protocols for DVT in patients with traumatic fractures, and make this consensus on the examination and assessment, treatment, prevention and preventive measures for DVT in patients with different fractures so as to provide a practicable approach suitable for China ′s national conditions and improve the prognosis and the life quality of patients.