Explicit Model for Solar Air Heaters Performance Assessment for Winter and Summer Operation

Abstract

Towards zero energy consumption buildings, designers need an easy tool to assess in the first stage of the design the performance of passive heating and/or cooling elements like the Trombe wall. In the present work a quasi-steady explicit model is developed for the operation of naturally ventilated Trombe wall for heating and for cooling (operation as solar chimney), based on ISO 13790. For the heating period, three configurations were considered: a) Without thermal mass for heat storage, b) With thermal mass wall and, c) With remote heat storage system of phase change materials. For the cooling period the (b) configuration was considered. The developed model is consisted by a set of equations that can be solved sequentially (no need for software and/or programming) and can be in the early stage of building design to maximize the yearly utilizable heat gains. The heat storage wall can increase the utilization of thermal gains from 15% to 46%. The use of phase change materials can increase these thermal gains up to 77%. The successful summer operation depends on the external climatic conditions and requires management of operation with an automation system when the thermal solar gains overweight the ventilation losses.