Performance of a novel liquid nitrogen power system

The Effect of Heat Exchange Fluid Composition on the Performance of a Liquid Nitrogen Engine System

“…In summary, the previous study [8] clearly demonstrated that introduction of HEF into the engine can enhance the engine work output and improve efficiency. However, the effect of varying HEF composition and thermophysical properties on engine performance have neither been investigated experimentally nor theoretically.…”

“…Recently, a novel liquid nitrogen (LN 2 ) engine system, which can provide simultaneous cooling and auxiliary power in refrigerated commercial trucks, has been investigated in detail [8]. The technology makes a significant departure from previous efforts by adopting the novel use of a heat exchange fluid (HEF) (typically composed of 60% antifreeze by volume and 40% deionised water by volume) which is directly mixed with the gaseous nitrogen (N 2 ) in the engine cylinder.…”

“…The concept of LN 2 /liquid air (LAir) hybrid system per se is not novel, as the first relevant patent is dated back to 1900 by Andersen [9] who proposed to generate power through both evaporation of LAir and combustion by injecting a controlled amount of liquid oxygen and hydrocarbons. Following Andersen's patent [9], various concepts for generating mechanical work were proposed to exploit both thermal and chemical energy of cryogenic liquids, including LN 2 , LAir and Liquified Natural Gas (LNG), as reviewed by Knowlen et al [10] and Christodoulou et al [8].…”

“…While that work proved the concept, the performance was low, with a specific work of up to 40 kJ/kg-LN 2 . A major improvement in the specific work of LN 2 engine systems was reported by the Dearman Engine Company (now called Clean Cold Power) and a prototype system (up to 172 kJ/kg) was demonstrated experimentally and reported in the literature [8]. This improvement was achieved by integrating a dedicated Heat Exchange Fluid (HEF) subsystem to enhance the in-cylinder heat transfer to the cold N 2 and increase the effective expansion ratio.…”

“…However, an external LN 2 evaporation system can cover the cooling needs for a refrigeration unit, while generating additional power by expanding the high pressure gaseous N 2 in a reciprocating engine. Christodoulou et al [8] reported a detailed experimental investigation of an externally evaporated LN 2 engine system with an integrated HEF system where LN 2 is fully evaporated externally and then introduced into the engine as a high-pressure superheated N 2 vapour [8]. Their work clearly showed the beneficial impact of HEF on engine work output and engine efficiency.…”