Development of a novel refrigerated transport system using a combination of liquid nitrogen expansion and mechanical vapour compression.

Most transport refrigeration systems use vapour compression cycles, powered by main or auxiliary Diesel engines. A minority use liquid nitrogen, using only the energy of low-pressure vapourisation. The system described uses a vapour cycle driven by a Dearman Engine, a highly efficient Rankine-cycle engine powered by the phase-change expansion of liquid nitrogen. The system uses the synergy between cooling of the vapour compression condenser and a novel heat exchange process in the cryogen expansion cycle, to deliver high efficiency. Analysis, test results and techno-economics show that a practical system can deliver significant savings in operating cost and life-cycle carbon compared to incumbents; the only exhaust is cold nitrogen, offering a significant benefit in local air quality.