Improvement of efficiency of a gaslift pump is required for lifting submarine resources economically. We propose a gaslift pump utilizing phase change of working fluid to improve the efficiency by avoiding air compression. A working fluid, which has a boiling point lower than surrounding temperature, is supplied as liquid to an evaporator near the bottom of a riser pipe through an adiabatic pipe. The working fluid boils at the evaporator due to heating from the surrounding liquid. The generated gas is injected into the riser pipe instead of compressed air and forms gas-liquid two-phase flow, by which the water is drawn from the bottom opening of the riser pipe. The working fluid is separated from the drawn water at the top of the pipe, and it flows into a cooler to supply the condensed liquid into the adiabatic pipe again. This pump needs the energy only to cool the working fluid, i.e. no energy is required for compressing gas. The feasibility of the pump is confirmed through the experiments using a prototype gaslift pump using a hydro-fluorocarbon as the working fluid. Prediction of the flow rate of drawn water is also carried out.
Hosokawa, S., Fujimoto, S., & Tomiyama, A. (2016). Gaslift pump making use of phase change of working fluid. Applied Thermal Engineering, 103, 1119–1125. https://doi.org/10.1016/j.applthermaleng.2016.05.010