Previous research has shown that interchange-fracture enhanced geothermal systems show desirable heat extraction performance. However, their parameter sensitivity has not been systematically investigated. In this study, a three-dimensional, unsteady flow and heat transfer model for an enhanced geothermal system with an interchange-fracture structure was established. The influences of pivotal parameters, including stimulated reservoir volume permeability, fracture spacing, fracture aperture, and injection flow rate on the thermal extraction performance of the interchange-fracture enhanced geothermal system were systematically researched. In addition, the economics of this system were evaluated. The results show that the heat extraction performance of the interchange-fracture system is significantly affected by a change of stimulated reservoir volume permeability and injection flow rate. Increasing permeability reduces electricity costs and improves economic income, while increasing the injection flow rate increases output power but hinders the long-term running stability of the system. Our research provides guidance for the optimal design of an interchange-fracture enhanced geothermal system.

Liquefied natural gas (LNG) needs to be gasified before supplied to the users, and considerable amount of cold energy, about 830 kJ/kg, will be released during this process. Recovery of LNG cold energy bears significance of energy-saving and environmental protection. Among the many ways of using LNG cold energy, power generation is the most effective and suitable one for large-scale applications. Many novel power generation cycles have been designed for utilizing LNG cold energy so far. This paper reviews the recent researches on LNG cold energy utilization in power generation, and discusses 15 novel power generation cycles utilizing LNG cold energy.