Observations collected in the Badan Jaran desert hinterland and edge during 19-23 August 2009 and in the Jinta Oasis during 12-16 June 2005 are used to assess three methods for calculating the heat storage of the5-20-...Observations collected in the Badan Jaran desert hinterland and edge during 19-23 August 2009 and in the Jinta Oasis during 12-16 June 2005 are used to assess three methods for calculating the heat storage of the5-20-cm soil layer.The methods evaluated include the harmonic method,the conduction-convection method,and the temperature integral method.Soil heat storage calculated using the harmonic method provides the closest match with measured values.The conduction-convection method underestimates nighttime soil heat storage.The temperature integral method best captures fluctuations in soil heat storage on sub-diurnal timescales,but overestimates the amplitude and peak values of the diurnal cycle.The relative performance of each method varies with the underlying land surface.The land surface energy balance is evaluated using observations of soil heat flux at 5-cm depth and estimates of ground heat flux adjusted to account for soil heat storage.The energy balance closure rate increases and energy balance is improved when the ground heat flux is adjusted to account for soil heat storage.The results achieved using the harmonic and temperature integral methods are superior to those achieved using the conduction-convection method.展开更多
Predictions for freezing heat transfer in a slab with convective boundary conditions at the cold surfaceare obtained from heat balance integral approximations, which consider conduction as the only modeof heat transfe...Predictions for freezing heat transfer in a slab with convective boundary conditions at the cold surfaceare obtained from heat balance integral approximations, which consider conduction as the only modeof heat transfer in both the solid and liquid and consider durations of precooling and freezing in theheat transfer process. The thermal penetration dimensionless parameter or is presented to distinguishtwO cases of freezing, and analytical results for α≥ 1 are given in this paper. An experimental investigation on freezing of water is reported for comparison with the one-dimensional conduction model toshow that experimental modeling for freezing heat transfer with convective boundary conditions usingPeltter devices is feasible. The comparison also demonstrated that the freezing rate in this case wasdecreased by natural convection in the liquid just as freezing with boundary conditions of the first kindand phase change approximately proceeds linearly with time rather than with square root of time atthe initiation of freezing.展开更多
基金Supported by the National Science and Technology Support Program of China(2012BAH29B03)National(Key) Basic Research and Development(973)Program of China(2009CB421402)
文摘Observations collected in the Badan Jaran desert hinterland and edge during 19-23 August 2009 and in the Jinta Oasis during 12-16 June 2005 are used to assess three methods for calculating the heat storage of the5-20-cm soil layer.The methods evaluated include the harmonic method,the conduction-convection method,and the temperature integral method.Soil heat storage calculated using the harmonic method provides the closest match with measured values.The conduction-convection method underestimates nighttime soil heat storage.The temperature integral method best captures fluctuations in soil heat storage on sub-diurnal timescales,but overestimates the amplitude and peak values of the diurnal cycle.The relative performance of each method varies with the underlying land surface.The land surface energy balance is evaluated using observations of soil heat flux at 5-cm depth and estimates of ground heat flux adjusted to account for soil heat storage.The energy balance closure rate increases and energy balance is improved when the ground heat flux is adjusted to account for soil heat storage.The results achieved using the harmonic and temperature integral methods are superior to those achieved using the conduction-convection method.
文摘Predictions for freezing heat transfer in a slab with convective boundary conditions at the cold surfaceare obtained from heat balance integral approximations, which consider conduction as the only modeof heat transfer in both the solid and liquid and consider durations of precooling and freezing in theheat transfer process. The thermal penetration dimensionless parameter or is presented to distinguishtwO cases of freezing, and analytical results for α≥ 1 are given in this paper. An experimental investigation on freezing of water is reported for comparison with the one-dimensional conduction model toshow that experimental modeling for freezing heat transfer with convective boundary conditions usingPeltter devices is feasible. The comparison also demonstrated that the freezing rate in this case wasdecreased by natural convection in the liquid just as freezing with boundary conditions of the first kindand phase change approximately proceeds linearly with time rather than with square root of time atthe initiation of freezing.
