A large number of low concentration methane gas is emitted directly into the atmosphere during the coal production, resulting in a serious waste of energy and the greenhouse effect. Aiming at the shortcomings of conve...
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The effect of groove size on heat transfer performance of a loop heat pipe (LHP) with flat evaporator was investigated experimentally, and the comparison of two different kinds of groove size was conducted under diffe...
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The hot corrosion tests of the austenitic TP347HFG in molten sulfates with and without external stresses were conducted at 700 and 750 oC. The corroded specimens of different conditions were investigated through measu...
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The nozzle exit position (NXP) is a significant parameter for an ejector. In this work, a two dimensional (2D) homogeneous CFD model is developed to simulate the two-phase ejector used in transcritical CO2 refrigerati...
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ISBN:
(纸本)9782362150128
The nozzle exit position (NXP) is a significant parameter for an ejector. In this work, a two dimensional (2D) homogeneous CFD model is developed to simulate the two-phase ejector used in transcritical CO2 refrigeration cycle and NXP is focused on. After model validation, the flow fields in ejectors with different NXPs are simulated and an optimal NXP is obtained. According to the numerical results, with the increase of the NXP, a higher velocity and lower pressure are achieved for the primary fluid in the suction chamber which enhances the entrainment of the secondary fluid. Oppositely, the flow area of the primary fluid at the mixer inlet increases with the NXP which reduces the secondary flow rate. A compromise between these two factors leads to the optimal NXP with the highest entrainment ratio under the same operating condition. The results are helpful to the optimal design and control of the ejector.
In this paper a dynamic model of transcritical CO2 ejector expansion refrigeration cycle with two-stage evaporation (EERC-TE) is established to track the transient response of system parameter at two regulation method...
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ISBN:
(纸本)9782362150128
In this paper a dynamic model of transcritical CO2 ejector expansion refrigeration cycle with two-stage evaporation (EERC-TE) is established to track the transient response of system parameter at two regulation methods which includes the vapour quality adjustment and the entrainment ratio adjustment. The effectiveness of system model is verified and the results show the predictions have a agreement with the experimental data. Based on the unit change of ejector nozzle throat area and volume flow rate of chilled water of the second evaporator, the dynamic responses of pressure in gas cooler, the first and second evaporator, mass flow rate of primary flow, entrainment ratio and vapour quality of separator inlet are compared. The regulation of ejector nozzle throat area causes relatively large system responses compared to that of chilled water flow rate of the second evaporator. This work is useful to guide system control and the improvement of system performance.
Two-phase flashing spray holds a special interest in the safety area. High pressure liquids or liquefied gases accidentally released from small hole in chemical or nuclear industry can form two-phase mixtures due to t...
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With the CPC integrated photovoltaic / thermal (PV/T) system as the research object, this paper studies the design techniques, builds experimental platform of the system and analyzes its thermal and electrical perform...
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ISBN:
(纸本)9781785610400
With the CPC integrated photovoltaic / thermal (PV/T) system as the research object, this paper studies the design techniques, builds experimental platform of the system and analyzes its thermal and electrical performance. Firstly, the basic architecture parameters of CPC is designed and the key factor which influences the concentrating uniformity of CPC is found via the software named lighttools simulation so that the light distribution uniformity of PV panel is improved. Secondly, the manufacture technique of PV/T collector is designed, including the determination of the size of PV module and the external and internal dimensions of the flat cassette collector. The entire PV/T collector is manufactured by means of direct lamination. Finally, according to the manufactured CPC and PV/T, the experimental platform of CPC integrated PV/T system, whose power is 1kW, is built. The thermal-electrical performance evaluation model of the experimental platform is established. The thermal-electrical performance of the experimental platform is tested and the results show that the water temperature of the outlet can be above 45°C and the total efficiency can reach 60%.
A two-way coupling three-dimensional Vortex-In-Cell (VIC) method is developed for the simulation of gas-solid turbulent flow. The evolution of vortex elements and the motion of solid particles are tracked in the Lagra...
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A two-way coupling three-dimensional Vortex-In-Cell (VIC) method is developed for the simulation of gas-solid turbulent flow. The evolution of vortex elements and the motion of solid particles are tracked in the Lagrangian frame, while the flow field is solved by the vorticity Poisson equation on the Eulerian grid. Two-way coupling is implemented by introducing a vorticity source term induced by the motion of particle. This method is applied to simulate the particulate jet generated by solid particles falling from a circular orifice into unbounded quiescent air. The simulation results agree well with the experiment conducted by Ogata, which confirmed the validation of this method. The simulation results demonstrate that the air velocity radial distribution due to the particulate jet satisfies Gaussian distribution. The particle flow rate has little influence on the spread of particles, while velocity of particles increases with increasing the particle flow rate.
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