Journal of Energy Engineering

To investigate the fuel flow control for starting a crankcase-injected two-stroke spark ignition (SI) engine that is fueled with rocket propellant 3 (RP-3), a fuel film compensation model for crankcase injection was presented on the basis of the fuel film theory. A discrete control algorithm was also given in this study. According to fuel film compensation, the control model of the fuel flow for the engine starting process was simulated. The simulation results showed that the fuel film compensator could ensure that sufficient kerosene fuel enters the engine cylinder. Starting experiments on a two-stroke crankcase-injected SI engine fueled with RP-3 were carried out with the cylinder temperature preheated to 50°C. As the estimated percentage of the fuel deposited on the wall was approximately 0.8, and the estimated value of the fuel film evaporation time constant was 1.2, the kerosene-fueled SI engine attained smooth engine starts with a fast transient speed response.

In this work, hybrid fuels consisting of diesel fuel, tung oil, and ethanol were made. The spray characteristics and engine performance of hybrid fuels were studied utilizing a spray visualization system under atmospheric conditions and an engine testing system respectively. The results indicated that the viscosity of tung oil could be reduced with the addition of diesel and ethanol. The quality of spray and atomization deteriorated when tung oil volume fraction was increased in the hybrid fuels but could be improved when ethanol volume fraction was increased. The brake specific fuel consumption and brake thermal efficiency of the hybrid fuels was higher than those of diesel fuel. With the increasing percentage of tung oil and ethanol in the hybrid fuels, a reduction in smoke and nitrogen oxide emissions and an increase in carbon monoxide and hydrocarbon emissions were observed at low engine loads.

The seawater source heat pump (SWHP) utilizes low-grade energy from seawater to satisfy heating/cooling requirements of coastal buildings. Compared with the open-loop SWHP system, the closed-loop system is more stable and reliable when used in cold regions because the seawater heat exchanger can mitigate icing and corrosion problems. This study established mathematical modeling for the seawater heat exchanger, which was validated by the experimental results, to estimate the heat transfer performance. The thermal performance of the seawater heat exchanger under different operating conditions was predicted, and the effects of several key parameters on thermal resistance were analyzed. The results revealed that the pipe wall thermal resistance of the original heat exchanger was the most important factor limiting the heat transfer. Hence, a cost analysis of the heat exchangers with different pipe materials was conducted, and the steel pipe with anticorrosive coating was proven to be optimal in reducing pipe wall thermal resistance and economy. The findings are useful in designing and optimizing the seawater heat exchanger and promoting the application of ocean thermal energy.