Advanced Materials Research Vols. 732-733

Abstract: Miniaturization and high-efficiency plays an important role in the further development of absorption refrigeration. In order to improve the mass transfer efficiency, liquid-gas ejector is intended to be used in refrigeration system. Experimental analysis of effects of non-structural factors on Liquid-Gas Ejector driven by aqueous LiBr solution is presented. Solution concentration, solution temperature, evaporator temperature and back pressure are varied to analyze the ejector performance. The results show that the large difference between refrigerant vapor pressure and partial pressure of solution enhances absorption of water into aqueous lithium bromide solution. The optimal solution concentration range is 56.61wt%~57.61wt% when the throat diameter of convergent-divergent nozzle is 1.5mm. Cooling capacity increases with the decreasing of back pressure.

Abstract: Flow field uniformity in the process of pressure pre-cooling can ensure fruit and vegetable pre-cooling effect. Flow field of pre-cooling packing boxes under 5 different opening modes were calculated through numerical simulation, including velocity distribution, temperature distribution and pressure distribution. The simulation results were also verified by experiment. Both theoretical and experimental results showed that the greater the external covering opening ratio, the faster the cooling. Temperature of the measure points away from the pressure fan side with a small opening ratio reduced more rapidly than that with a big external opening ratio. The opening ratio of the external covering should be lower close to pressure fan side than that away from it. Therefore in actual pre-cooling work, the opening ratio close to pressure fan side should be lower than that away from it. The diameter of the openings distributed at the lower part should be smaller than that of the openings distributed at the upper part of the external covering and this can overcome pre-cooling non-uniformity between upper and lower layers.

Abstract: The numerical model for ZGM95 medium speed mill is built and the inner flow fields are simulated by employing the commercial code of FLUENT. The results show that the distributions of the static pressure and the flow rate are not uniform for 36 nozzle rings due to the primary air entering the mill only from one side. Two modified structures are assumed to improve the mills performances and the corresponding models are simulated further. The flow fields are still not good enough and the pressure drop increases sharply in the mill when blocking several nozzle rings, and this structure is not recommended if the amount of pulverizer rejects is not extremely huge. The structure with double-inlet can improve the distribution of the flow fields effectively in the mill and few pressure drops of the mill increase. However, the feasibility of the double-inlet structure is also depends on the field conditions. The pressure drop will be less and the flow fields will be better when adopting the horizontal inlet duct instead of the inclined one.

Abstract: In this paper, explicit difference scheme, implicit difference scheme and characteristics method are separately used to simulate the transient flow in products pipeline. The simulation result can be used to prevent water hammer in the pipeline of unsteady situation and to improve the efficiency and safety in oil transmission systems. And then, the stability and accuracy of the three methods are compared by adopting different time steps. For explicit difference method, large fluctuation may occur in case of large time step. For implicit method, the result is weakly affected by time step, only if the relaxation factor selected is reasonable. For characteristics method, the results have a high convergence speed and precision. The results show that, in the situation of valve shut down in terminal, it takes about 1.1×10⁴ seconds to return to a new steady state.

Abstract: Water mist fire suppression system is widely used in many places, for its little damage and greatly reduces the cost of extinguishing fire. But because of the intricate extinguishing mechanism of water mist, it is difficult to design an optimal water mist fire suppression system in a typical place. With the rapid development of computer technology, computational fluid dynamics (CFD) has already been proved to be a useful and powerful tool in fire safety science. Fire Dynamics Simulator (FDS) is used to simulated the interaction of water mist and fire in a typical fire scenario in this paper. Two design schemes of water mist system are compared to prove which one is better. Through simulated by FDS on these two cases, the water mist system with 4 sprinklers is suited in the restroom.

Abstract: It’s introduced the method of calculation, modeling techniques and solution techniques of the aerodynamic performance of engine cooling fan. Based on a fan-tunnel test, the relation between static pressure, power, efficiency with volume flow is calculated in Fluent. It is proposed a few improved models and compared the calculations of different models. It’s analyzed the problems and reasons in the calculations of models and proposed the improved methods in fan test and numerical calculation. Keywords:Cooling Fan, Aerodynamic Performance, Models

Abstract: The research of anti-slip control for slurry pump is to prevent the cavitation of pump,protect flow passage components of pump from cavitation corrosion.Through the analysis,the size of the inlet velocity is regarded as the characterization whether pump cavitation.Calculate the five kinds of inlet velocity when the slurry pump is in the normal work, make the procedure is versatility. PLC programs are compiled and imported into hydraulic-pneumatic experimental platform,experimental platform simulates the results of pump system is accord with anti-slip control requirements.The program is used in slurry pump avoids the occurrence of cavitation phenomenon and simplifies the complicated site operation.

Abstract: Introduce the principle and advantage of ice storage air conditioner. Take an project in Shenzhen for example, analyze it’s circulate mode and compared the cost of ice storage air conditioner with routine air conditioner at the same load. The results show that the project should adopt ice storage air condition and this is economically rational.

Abstract: Integration of several in-house heat stations containing of multiple boilers of different capacity and energy carriers can be economical profitable. This study contains further analyze and development of previous work by Riise and Sørensen [1-3]. Boiler start-up costs effect of the overall energy cost has been investigated and found to have an impact of boiler configurations in a system based on lowest specific running energy cost. A study of operational hours of boilers indicates if boilers can be dismounted form the integrated system. It is also performed simulations for lowest energy consumption instead lowest energy cost. Finally a heat pump model is introduced and analyzed. Introduction of the heat pump reduces the total energy cost even if the heat sink is increased with a fourth building.

Abstract: A R32/CO₂ cascade refrigeration cycle was analyzed thermodynamically, the results show that: Under given working conditions, there exists the best condensing temperature of the low-temperature circuit to make the maximum COP of the cycle. The lower evaporating temperature is, the lower the best condensing temperature of the low-temperature circuit is. Under the same evaporating temperature, COP increases and m_H/m_L decreases along with condensing temperature decreasing, under the same condensing temperature, COP decreases and m_H/m_L increases along with condensing temperature decreasing. To reduce the temperature difference in the cascade-condenser can increase COP and decrease m_H/m_L.