Hongbo Tan

Design and Optimization of an Improved Small-Scale Liquefaction Process for the Natural Gas Pressure-Reducing Station in Pipelines

AbstractA small-scale liquefaction process without any extra energy consumption was proposed to liquefy a part of natural gas in the pressure-reducing station. A heat exchanger network was integrat...

Experimental study on a self-refrigerated auto air conditioning system based on LNG-fuelled trucks

The authors proposed and investigated a novel self-refrigerated auto air conditioning system for Liquefied Natural Gas (LNG) fuelled trucks. The cold energy in cryogenic fuel, LNG, was drawn and reused to cool the drivers cab. After theoretical analyzing the available cooling capacity and thermal performance of the new system, the refrigerating performance including cold load, temperature characteristics of the heat exchangers were investigated experimentally under different operating conditions. The results showed that (1) the recovered cooling capacity could cover the heat load of drivers cab (4.1 kW) when LNG consumption rate is larger than 20 kg/h; the maximum cooling capacity is up to 8.746 kW which is about twice of the cooling demand; (2) in order to supplying adequate cooling capacity for the drivers cab, the shaft power of the equipped engine should be not less than 105 kW which accounts for 37.5% of its maximum power capacity; (3) The heat exchangers of the proposed system operated properly, and the desired cooling recovery performance was achieved successfully. However, the LNG vaporizer should be designed more carefully and accurately. The study indicates that the self-refrigerated air conditioning system for LNG-fuelled trucks is feasible and the cooling capacity storage methods must be employed to adjust the mismatch of the cold supply and demand caused by the fluctuation of the LNG consumption rate.

Optimization and comparison of boiling-off gas re-liquefaction processes for liquid ethylene vessels

Liquid Ethylene Gas (LEG), which is stored at -103.7 °C and 0.1 MPa, is usually transported by vessels with a vacuum insulated tank over oceans and lakes, or along rivers. A part of LEG would be vaporized into Boil-Off Gas (BOG) due to the inevitable heat leakage. To guarantee the vessels safety, an on board re-liquefaction plant is widely equipped to condense the BOG and return it to the tank. Improving the energy efficiency of the re-liquefaction system has attracted more and more attention. In this paper, three potential BOG re-liquefaction processes have been analyzed based on a simulation model of Aspen HYSYS V7.2. The effects of the ethylene storage pressure, propane condensing temperature, propane evaporating pressure, intermediate pressures of refrigeration and liquefaction cycles on the system performances were analyzed. Employing the optimizer of Aspen HYSYS, the optimal design conditions of the researched processes were determined. A cascade process which is composed of two subsystems, a two-stage compression refrigeration cycle using propane as working fluid and another two-stage compression ethylene liquefaction cycle, was proved to be superior to other processes. This work could provide some reference for choosing the BOG re-liquefaction processes for LEG vessels.