Experimental investigation of the effects of add-on fan radiators on heat output and indoor air temperature

Conventional panel radiators are widely used to satisfy indoor heating demands thanks to the heat transfer from the radiator by natural convection and radiation. To increase the heat output from an existing radiator without increasing the supply temperature or replacing the radiator with bigger ones, fans can be mounted below the radiator and this installation carries out heat transfer from the radiator by forced convection. The heat output increases and the changes in the rates of heat transfer mechanisms of these radiators, which are called add-on fan radiators, were experimentally investigated under different supply temperature and fan speed conditions. In addition, the effects of add-on fan radiators on the air temperature values in the test room were also examined. The results show that the addition of the fan unit increased the heat output from the radiator considerably. Also, more enhancement was observed at lower supply temperature conditions. It was also concluded that although the rate of heat output by natural convection and radiation decreased in add-on fan radiators, the total heat output from the radiator was higher than the conventional radiators due to the heat output arising from forced convection prevent this decrease.