Analytical function describing the behaviour of a thermocline storage tank: A requirement for annual simulations of solar thermal power plants

作者：Bayon Rocio^*; Rojas Esther

来源：International Journal of Heat and Mass Transfer, 2014, 68: 641-648.

DOI：10.1016/j.ijheatmasstransfer.2013.09.070

• Solar thermal power plant
• Thermal storage
• Sensible heat
• Thermocline
• Analytical solution
• Logistic Function

Thermocline tank behaviour during dynamic processes of charge/discharge and stand-by periods has been described in dimensionless form by means of the Logistic Cumulative Distribution CDF). The Logistic-CDF parameter, S, has been correlated with both thermocline tank features and operation conditions (i.e. dimensionless velocity, v*, and time, t*) with the help of a single-phase one-dimensional numerical model previously developed and validated. For the dynamic processes, it has been found that S becomes independent on v* when v*> 2500, but it always increases proportionally with root v*t* due to the progress of thermocline zone inside the tank. For adiabatic stand-by periods, in which v* = 0, S parameter proportionally increases with root t* whereas z(c)* varies in order to keep constant the stored energy inside the tank. In terms of thermocline thickness it has been demonstrated that it is proportional to S parameter but its exact value strongly depends on the temperature accuracy that determines thermocline zone limits. This parameterised Logistic-CDF provides a general analytical equation for the outlet temperature of the storage liquid, which allows implementing thermocline storage systems in the annual performance simulations of solar thermal power plants.

• 出版日期2014-1