Simulation Analysis Of Heat Pump System In CO₂ Applied To THIC

In this paper, based on the research of the CO2, transcritical CO2 refrigeration cycle and independent temperature and humidity control system, indicated that:(1) CO2 has the following advantages:environmental protection, good stability, high refrigerating efficiency, high thermal efficiency, low critical temperature, and so on; (2) Whether transcritical CO2 refrigeration cycle is separate refrigeration or heating alone, there are quantities of energy dissipation. When separate refrigeration, a considerable loss of temperature glide in the air cooler has produced; when heating alone, a portion of the available energy loss due to exhaust; (3) Independent temperature and humidity control system provides convenience for use of the high temperature cooling source and improves the system performance, but the energy source of independent dehumidification system become the obstacles in the development of it.In consideration of these two complementary factor of liquid desiccant regeneration need a lot of energy and the air cooler can produce high temperature hot water by the temperature glide in transcritical CO2 refrigeration cycle. This text will be transcritical CO2 refrigeration cycle applied to independent temperature and humidity control system. Accordingly, transcritical CO2 refrigeration cycle could both cooling and heating and the energy source of independent dehumidification system was met. So as to achieve a win-win situation and improve the COP of the system and have the effect of energy conservation and environmental protection. Because of experimental conditions, this paper Uses simulation to study transcritical CO2 refrigeration cycle and the simulation software is from danish CoolPack.Firstly, this paper introduces the function and principle of CoolPack, and then, based on the related researches which make use of CoolPack as auxiliary research and comparative result of simulation data of CoolPack and experimental data, thereby, demonstrates the possibility of the CoolPack. Because of, mainly, this article through simulation to analyze the critical CO2 refrigeration cycle system. So, only the simulation software was viable that The results of the analysis is feasible.Afterwards, this paper introduces the operational principle of CO2 transcritical cycle in the integrated air conditioning system of CO2 transcritical cycle with temperature and humidity independent control. And the theory analysis and simulation for system is done by establishing the corresponding mathematics physical model. At the same time, using 100kW refrigerating quantity as an example, made simulation to the system combine with Coolpack. Simulating vapourization temperature TE, gas cooler outlet pressure P, gas cooler outlet temperature T4 of CO2 transcritical cycle, and discover the influence of the simulated result. Simulation analysis shows that:(1) there is an optimum high side pressure (Popt) that makes COPsystem to be maximized, the simulation results and the correlation(Popt= (2.778-0.0157Tg)T4+(0.381TE-9.34)) mentioned in the related literature showed that the influence factor of Popt are T4 and Te and the T4 is the main influence.(2) In the process of simulation, we had recorded the COPcooiing, QGC, W, and so on. At the same time, we got that COPheating=QGC/W, so that, the system was both cooling and heating and we can get that COPsystem=COPcooiing+COPheating. The results found that the change is consistent.(3) TE and T4 were confirmed, before the optimum high side pressure (Popt), the COPsystem increases with the increasing P, and after the optimum high side pressure (Popt), the COPsystem decreases with the increasing P.(4) TE and P were confirmed, the COPsystem decreases with the increasing T4.(5) T4 and P were confirmed, the COPsystem increases with the increasing TE.Simulation analysis for the second time was simulated on the certain optimum high side pressure (Popt). So that study the change between the COPsystem, TE, T4 and T2. Researches show that:the change of T4 Had a great influence on COPsystem. When keeping their Popt, the COPsystem decreases rapidly with the increasing T4 and increases with the increasing TE. But the rise of COPsystem becoming smaller when increase T4. TE was confirmed, the T2 increases with the increasing T4. But when T4 was confirmed, T2 decreases with the increasing TE. the height of T2 which affects the height of the temperature of hot water from the new integrative system. According to the simulated data and the needs of the system, the range of values of T4 was 30℃ to 40℃, and COPsystem was inverse relation with T4. So that the COPsystem became higher when the value of T4 become smaller. Thus it can be seen that higher T4 at the cost of higher Popt and lower COPsystem. From the point of view of the system, in the case of meeting the actual demand that should decreases T4. In case this requirement can not be satisfied, don’t blindly pursue high temperature. Otherwise, it will do more harm than good.Conclusion the simulation results, according to the simulation analysis of this article and the practical demandin engineering, design a air-conditioning system with CO2 across critical refrigeration cycle(heat pump). After simulate we know, Te=12℃, T4=35℃, P=8.5MPa, T2=82.9℃, COPsystem=10.097. Discharge temperature of compressor with 82.9℃ can prepare hot water with 70℃ supply to liquid desiccant regeneration, in the meantime, the COPsystem much larger than traditional air-conditioning system which separate refrigeration or heating alone. The study results show it is of energy saving.In this paper, the research results provides the basis of a simulation study of CO2 across critical refrigeration cycle (heat pump).At the same time, provide a reference for practical projects in the future.