In this paper,the performance analysis of recharging the borehole by means of exhaust-air energy is carried out.The results show that a vertical borehole used as heat source for a Ground Source Heat Pump(GSHP)can be r...In this paper,the performance analysis of recharging the borehole by means of exhaust-air energy is carried out.The results show that a vertical borehole used as heat source for a Ground Source Heat Pump(GSHP)can be recharged in high efficiency.With equal heat transfer capabilities of exhaust-air coil and borehole collector,the system provides a maximum overall efficiency.However,due to ground infinite capacity,the optimum brine flow rate is different from conventional two-exchanger system.The recharging system provides two peak overall efficiencies when the capacity ratio Cr=5 for laminar flow and Cr=15 for turbulent flow respectively.The overall efficiency is independent of exhaust-air temperature and undisturbed ground temperature,although the fluid properties depend on temperature.In practical system lower ethyl percentage brine should be chosen if the freezing point meets the system request,which can provide a higher overall efficiency.展开更多
Previously,we had identified the various dynamic mechanisms of a wide range air to fuel ratio sensor operated in the engine exhaust by using the transfer function approach.In this study,we utilized these results to mo...Previously,we had identified the various dynamic mechanisms of a wide range air to fuel ratio sensor operated in the engine exhaust by using the transfer function approach.In this study,we utilized these results to model the real time sensor response to an engine exhaust excursion.In the fitting,we identified a new dynamic mechanism,which was not detected in the previous transfer function study.This new dynamic occurred at the stoichiometric point when the engine changed from rich to lean.This new mechanism involved the depletion of the adsorbed fuel species on the electrode surface by an oxidation process. The dynamics of this effect depends on the ratio of the diffusion flux of the sensor-coating layer to the total adsorbed gas species on the electrode surface.The smaller the ratio is,the slower the dynamic mechanism will be.展开更多
A numerical analysis of a batch-type reheating furnace with and without thermal load was carried out using the Computational Fluid Dynamics technique. The furnace has two premixed burners and methane is used as fuel. ...A numerical analysis of a batch-type reheating furnace with and without thermal load was carried out using the Computational Fluid Dynamics technique. The furnace has two premixed burners and methane is used as fuel. Previous to the numerical experiments, a mesh convergence test was carried out and the average internal furnace temperature and the exhaust gases temperature were monitored as function of the number of cells in the discretized system. The influence of the Air/Fuel ratio, the position of the burners, and the thermal load on the average internal temperature, the exhaust gases temperature, and the molar fraction of methane and oxygen in the exhaust gases was numerically explored.展开更多
文摘In this paper,the performance analysis of recharging the borehole by means of exhaust-air energy is carried out.The results show that a vertical borehole used as heat source for a Ground Source Heat Pump(GSHP)can be recharged in high efficiency.With equal heat transfer capabilities of exhaust-air coil and borehole collector,the system provides a maximum overall efficiency.However,due to ground infinite capacity,the optimum brine flow rate is different from conventional two-exchanger system.The recharging system provides two peak overall efficiencies when the capacity ratio Cr=5 for laminar flow and Cr=15 for turbulent flow respectively.The overall efficiency is independent of exhaust-air temperature and undisturbed ground temperature,although the fluid properties depend on temperature.In practical system lower ethyl percentage brine should be chosen if the freezing point meets the system request,which can provide a higher overall efficiency.
文摘Previously,we had identified the various dynamic mechanisms of a wide range air to fuel ratio sensor operated in the engine exhaust by using the transfer function approach.In this study,we utilized these results to model the real time sensor response to an engine exhaust excursion.In the fitting,we identified a new dynamic mechanism,which was not detected in the previous transfer function study.This new dynamic occurred at the stoichiometric point when the engine changed from rich to lean.This new mechanism involved the depletion of the adsorbed fuel species on the electrode surface by an oxidation process. The dynamics of this effect depends on the ratio of the diffusion flux of the sensor-coating layer to the total adsorbed gas species on the electrode surface.The smaller the ratio is,the slower the dynamic mechanism will be.
文摘A numerical analysis of a batch-type reheating furnace with and without thermal load was carried out using the Computational Fluid Dynamics technique. The furnace has two premixed burners and methane is used as fuel. Previous to the numerical experiments, a mesh convergence test was carried out and the average internal furnace temperature and the exhaust gases temperature were monitored as function of the number of cells in the discretized system. The influence of the Air/Fuel ratio, the position of the burners, and the thermal load on the average internal temperature, the exhaust gases temperature, and the molar fraction of methane and oxygen in the exhaust gases was numerically explored.
