Design and Development of Stand-Alone Water Filled Radiator System for Built Environment Applications

On an average the temperatures in the UK are low and drive the need for space heating, to maintain thermal comfort in built environments. As per the climate change act of 2008, by year 2050 UK committed to reducing its GHG (Green House Gases) emissions by 80% from a baseline of 1990 [4] with an intermediate goal for year 2020 to reducing emissions from homes by 29% from a baseline of 2008 [5]. There have been significant developments in legislation, energy efficiency of building innovation in insulation but it is important to investigate the trends and improvements in the heating systems themselves.

The losses in central heating systems are due to intermittent heating - accounting for approximately 10%, distribution losses - accounting for approximately 5% and losses due to separate hot water storage requirements to meet hot water demands from the same boiler - approximately 2kW. Another significant loss factor is heat loss from the network of pipes carrying hot water to the radiators.

Stand-alone radiators have presented themselves as a viable alternative to central heating systems by providing modularity, flexibility and controllability. Although there are several systems commercially available there is no product or research available on water filled stand-alone radiator systems.

A systematic study on viability of water filled stand-alone radiator is undertaken and a new stand-alone water filled radiator has been developed which offers the benefit of a central heating radiator system without the complexity of plumbing, installation and maintenance. In the new product development process, both mechanical and hydraulic considerations have been accounted for to ensure a safe, robust and commercially viable product is developed.

Detailed experimental evaluations of radiators under different flow configurations and flow rates for two radiator sizes have been carried out. The results obtained from the investigation have been quantified and graphically represented. Two key parameters to quantify pressure loss and pressure variations in a radiator have been developed. Relationship of pressure drop to flow velocity has been developed and a non-dimensional parameter, loss co-efficient K for radiators has been developed.

Detailed CFD based analysis to quantify the effect of radiator size and the port diameter under different flow configurations and flow rates has been carried out. The results obtained from the investigation have been quantified and graphically represented. A non-dimensional geometric factor has been developed to account for the effect of radiator size on performance parameters. A unique relationship has been established between loss co-efficient and port diameter to quantify the influence of inlet and out port diameters.

A detailed investigation of the various costs involved in heating a room using a stand-alone radiator system has been carried out and a radiator sizing and cost estimation process has been developed for stand-alone radiator. A methodological approach to predict cost for water filled stand-alone system has been developed which accounts for manufacturing cost and operation cost. A cost comparative study of central heating system and a stand-alone has been conducted to quantify cost benefit of one system to the other.