Advanced Materials Research Vols. 1070-1072

Abstract: A simulation of a new regulating valve designed for pneumatic conveying pipelines is carried out in this paper. This simulation uses SOLIDWORKS to build the valve model ICEM-CFD to generate the mesh, and FLUENT to numerically simulate the fluid field in pipeline under different opening degrees of the valve. The simulation results show that the new regulating valve has good regulation characteristics which can effectively regulate pipe resistance.

Abstract: Control equations were dissociated by the finite volume method, and the closed turbulence model equations were solved, and the different forms of flow characteristics and leakage condition in lateral tooth seal in turbine were analyzed by using numerical methods. The results show that the leakage rate of the lateral tooth steam seal with a single low tooth is less than that of the lateral tooth steam seal with double low teeth under different import pressure. And the leakage rate of the lateral tooth steam seal with a single low tooth or double low teeth and bottom teeth are slightly more than those without bottom teeth. It provides theoretical reference and technical support for the engineering design and transformation of steam seal in the turbine.

Abstract: Based on Navier-stokes equations, Weiss-Smith matrix preconditioning method is implemented within pseudo time derivative term. AUSM+-up family schemes and LU-SGS implicit iterative method were used to solve low speed flows and were compared with literature data and theoretical value. Through comparing calculation with the literature data and theoretical value, The Results showed the preconditioning algorithm can be applied efficiently to the low speeds flow field ,All these works built foundations for further application of chemical flows.

Abstract: The objective of this study is to experimentally investigate the mixed jet and oxygen transfer behavior of a vertical orifice nozzle. The experimental apparatus consisted of an electric motor-pump, an orifice nozzle, a circulation water tank, an air compressor, a high speed camera unit and controlling or measuring accessories. The entrainment ratio was calculated using the measured primary fluid flow rate and suction air flow rate with primary flow pressure. The visualization image of vertically injected air and mixed jet issuing from the orifice nozzle was analyzed qualitatively. As the air compressor pressure increases, the penetration length of mixed jet decreases and the mass ratio and dissolved oxygen concentration increase.

Abstract: Viscosity, as one of important performance indexes of liquid-phase heat transfer fluids, its measurement methods and instruments have developed greatly in recent years. This paper introduces the traditional methods and theory of measuring liquid-phase heat transfer fluids’ viscosity as well as summarizes the development of measuring liquid-phase heat transfer fluids viscometer at home and abroad.

Abstract: The paper presents the study on the control optimization of the central cooling plant system including thermal chilled water energy storage (TES) tank in a high-tech building consists of office area, clean room and lab space. The optimized control sequences were implemented on the cooling tower staging, cooling tower fan/condenser water pump/primary chilled water pump staging and speed control, chiller staging, TES pump speed and TES modulation valves control, and secondary chilled water loop differential pressure control. The proposed control effectively resolved the problem of fluctuation in the secondary chilled water supply temperature during charging cycle and temperature increase during the discharging cycle. The number of primary chilled water pumps, condenser water pumps and cooling tower fans were also reduced to minimum after the optimization. Implementation of optimized control sequences is predicted to have an annual electricity savings of 856,125 kWh, which is about 20% of the total central plant energy consumption.

Abstract: This paper proposed a prediction approach for the performance of the mechanical draft wet cooling tower based on artificial neural network (ANN). The inlet water temperature, the ambient wet bulb temperature and the ratio of water to air mass flow rate in the cooling tower were selected as the input parameters of a four-layer back propagation neural network (BPNN) to predict the temperature of the water at the tower outlet. After the test of the available data set, the BPNN results in a correlation coefficient of 0.9 between the predicted and experimental values. Thus the prediction performance is good and such prediction approach proves to be feasible and effective.

Abstract: Based on experimental platform of the evaporative cooling system and a large number of experimental data, the influence of air relative humidity and dry bulb temperature on the energy consumption ratio (ECR) of the evaporative condenser is studied. Resorting to the test data, linear, quadratic and cubic fitting surfaces are used to get the function of energy consumption ratio with two variables, dry bulb temperature and relative humidity. The fitting and validation results show that the quadratic surface approaches the real data best among the three manners.

Abstract: In order to improve the degree of digital urban central heating system in our country、manage many heat exchangers in the central heating system and timely and accurately diagnose with scale or jam faults of heat exchangers in the operation process, from the viewpoint of engineering application, this paper established the intelligent fault diagnosis system of plate heat exchanger, aimed at “the urban heating system intelligent decision-making platform development and demonstration ”project. Plate heat exchanger scale or jam fault diagnosis model is established based on real-time monitoring. Meanwhile association between pressure drop and flow of plate heat exchanger is given and applied to an actual plate heat exchanger for calculation and experimental verification. Results show that the fault diagnosis model can basically meet the requirements for engineering application,has a strong applicability and has a broad application prospect in the fault diagnosis system of plate heat exchanger.

Abstract: To obtain the influence of the neighbour room heat transfer on the radiator heat transfer characteristics and indoor thermal environment, a new k-ε model is used to numerically simulate the radiator surface heat transfer ability, indoor velocity field and temperature filed at different neighbour room heat transfer temperature differences. The results indicate that both the radiator surface temperature and the average Nusselt numbers on radiator surface are approximately increasing with the increasing neighbour room heat transfer temperature differences when the indoor average temperature is up to 18°C. At the same neighbour room heat transfer temperature difference, the local heat transfer ability is decreasing gradually from the bottom to the top of the radiator surface. The temperature gradient close to the floor is decreasing with the increasing neighbour room heat transfer temperature difference and the indoor temperature is tending to be more homogeneous. And the velocity gradients close to the ceiling and the internal surface of east wall are higher for the case that the neighbour room heat transfer is considered.