Experimental analysis of a novel concept of a “thermally driven” solution pump operating a small-capacity ammonia/water absorption heat pumping system

• A novel thermally driven solution pump for ammonia/water absorption heat pumps has been developed.
• The pump has been experimentally investigated in a commercially available absorption chiller.
• A comparison of the chiller using an electrical and the thermal solution pump is presented.
• The COP of the considered chiller using the thermal pump was reduced by at least 15%.
• This novel pump works without any electricity demand and can be easily integrated.

Only a few electrical solution-pumps are available on the market suitable for ammonia/water absorption heat pumping systems with an evaporator capacity lower than 20 kW. In order to improve this, a “thermally-driven” solution-pump is proposed, offering several advantages, as e.g. an oil-free, simple and leak-proof design. “Thermally-driven” means this pump is driven by a power process within the absorption heat pumping-cycle instead of electricity. The experimental analysis of this novel pump operating in a commercially available ammonia/water-absorption chiller shows that it can be easily integrated and works without any relevant operating limits. However, the measured COP of the considered chiller is decreased by at least 0.1 (15%) by this thermal-pump compared to the existing electrical-pump. Nevertheless, thermal energy (e.g. cost and CO2-free waste heat) can be used to drive this pump and due to lower production cost it can be an interesting alternative from an economical and ecological point of view.