Ammonia–water absorption cycle: a prospective way to transport low-grade heat energy over long distance

The ammonia–water absorption cycle could transfer thermal energy into chemical energy by the change in solution concentration, which low-grade heat released by industry-concentrated areas could be utilized to provide heating or cooling in the user site over long distance. No heat insulation is required for the transportation pipelines and the energy consumption is reduced greatly. The simulation researches show that thermal coefficient of performance (COP) is at 0.5 and exergy efficiency is >0.2 when generation temperature is at 110°C to provide cooling in summer; thermal COP is at 0.6 and exergy efficiency is >0.3 to provide heating in winter. Electrical COP as high as 50 could be realized if the transportation distance is >50 km. Therefore, the COP of the system is determined by thermal COP (nearly equal). An experimental prototype has been built to testify this theory. Thermal COP is 0.43 when chilled water at 8°C is obtained in summer. In winter, thermal COP is 0.45 when hot water at 58°C is obtained. The deviations between experimental and simulation results are ∼20%. The economic assessment based on the reasonable assumptions shows that the investment cost of the transportation pipelines of a 500 MW, 50 km system could be recovered within 15 months, in which the whole system costs could be recovered within 4 years. Copyright , Oxford University Press.