Investigation on the thermal performance of a composite Trombe wall under steady state condition

•A composite Trombe wall is proposed that combined with a water wall.•Low-temperature water can be directly utilized in the composite Trombe wall.•The energy and exergy analysis are conducted.•Impacts of various key parameters on the thermal performance are numerically studied. A composite Trombe wall is proposed which combines the water wall with the traditional Trombe wall. Computational fluid dynamics models for different types of Trombe walls were developed to investigate the flow and thermal performance. A good agreement was achieved between simulation results and relevant literature's data. The result shows that the Water Trombe wall could achieve best thermal performance. It can improve the operating efficiency during daytime. The thermal efficiency of the Water Trombe wall is 3.3% higher than the traditional Trombe wall at certain conditions. At nighttime, this structure has the advantage to directly utilize low-temperature water for decreasing building's heat loss. Under low irradiation conditions, the efficiency is 7.2% higher than the traditional Trombe wall. In simulated conditions, the results indicate that the Water Trombe wall can reduce heat loss by 31% compared with the traditional Trombe wall at night. The influence of temperature and velocity of low-temperature water was studied. The mass flow rate of water has minor effect on thermal performance of the Water Trombe wall.