A general model for predicting the airflow rates of a vertically installed solar chimney with connecting ducts

摘要

A general model is developed for solar chimneys with the use of a plume of constant thickness representing thermal boundary and the use of a momentum equation in the plume. A set of correlations between the plume thickness and the channel Reynolds number, defined by the plume velocity and channel hydraulic diameter, are proposed. There was a reasonable agreement between the model and 15 measured datasets in the range of Reynolds number from 17 to 23,151 and Rayleigh number at the half of the chimney height from 4.54x10(9) to 2.12x10(14). The correlations show that the channel free convection is a mixed flow of free convection (dependent on Ra) and a forced channel flow (dependent on Re-ch). The critical Rayleigh number at the half of the chimney height and the critical Reynolds number are consistent with those of natural free convection and forced channel flow, respectively. The plume model with the proposed correlations can serve as a general model for predicting the mass flow rates of vertical, square-channeled solar chimney systems with connecting ducts. (C) 2020 Elsevier B.V. All rights reserved.