Hong Guang Zhang

Study of Parameters Optimization of Organic Rankine Cycle (ORC) for Engine Waste Heat Recovery

Energy saving and environment protection are two most important issues that today’s internal combustion engine industry must tackle with. Lots of heat energy waste with the exhaust gas when the engine is running. Organic Rankine cycle (ORC) is a good method to recover the waste heat of the engine exhaust. In this paper, the mathematical model of ORC was built up in Matlab and the parameters were optimized using genetic algorithm (GA). Eight pure component organic working fluids were selected and compared. The results indicate that the evaporating pressure of the working fluid and the condensing temperature are two important parameters for ORC; the super heater also can enhance the system thermal efficiency slightly.

Study on the Performance of the Organic Rankine Cycle System with Internal Heat Exchanger under Vehicle Engine Various Operating Conditions

Through experiment, the variation of the exhaust energy of the vehicle diesel engine is studied, a set of vehicle diesel engine-organic Rankine cycle (ORC) combined system with internal heat exchanger (IHE) is designed, the zeotropic mixtures R416A is used as the working fluids for the ORC system with IHE, by theoretical analysis and numerical calculation, the variation of the vehicle diesel engine-ORC combined system with IHE under entire operating conditions of the diesel engine is studied, the calculation results show that, when engine is operating at high speed and high torque, the performance of the vehicle diesel engine-ORC combined system with IHE is higher.

Energy Storage and Deposition Characteristics of Spark Ignition System

Time-resolved current and voltage measurements for an inductive automotive spark system were made. The measurements were made in air for a range of charge time from 1-8ms, at ambient temperatures. Primary current was measured, so the primary energy can be calculated. Current and voltage signal of secondary circuit was detected, from which the spark energy and energy transformation efficiency can be calculated. Test results show that: when the charge time is 6ms, both the primary energy and spark energy reaches to saturation value, does not advanced any more with the charge time increasing; and the energy transformation efficiency is at an appropriate range.

Effects of Engine Operating Parameters on Lean Combustion Limit of Hydrogen Enhanced Natural Gas Engine

An experimental study was conducted on a S.I. engine fueled by compressed natural gas and hydrogen blends (HCNG), in order to test different engine operating parameters that affect lean combustion limit (L.C.L) of HCNG engine. Firstly, constant ignition timing and ignition timing under maximum L.C.L (L.L.T) conditions were compared, then L.L.T conditions were adopted in this paper. The results indicated that for each condition, neither over-retarded nor over-advanced ignition timing are advised in order to achieve leaner combustion. L.C.L increases with hydrogen fraction in the blends, and slightly increases with throttle opening, while decreases when the engine speed is raised

Research of Two Stage Single Screw Expander Organic Rankine Cycle System Scheme Based on the Waste Heat Recovery of Diesel Engine’s Exhaust Gas

According to the analysis of heat balance, about 1/3 of the fuel combustion heat is taken away into the ambience by exhaust gas of diesel engine. In this article, to improve the using level of the fuel’s combustion heat, a two stage single screw expander organic Rankine cycle (ORC) system has been used to recover the waste heat from exhaust gas of a certain turbine diesel engine. In this article, physical model of the recovery system was built at first, then the T-S curve was drawn, at last, REFPROP was used to calculate thermodynamics parameter in different state point of this system, and analyze the whole system’s thermodynamics character. By analyzing, the evaporation temperature of this system should be optimized to get the relatively evaporation press; by calculating, it could be seen that the middle heater in this system should be taken away to improve the economy of this scheme. This scheme should supply a direction for the exhaust heat recovery of diesel engine.

Modeling a Finned Tube Evaporator for Engine Exhaust Heat Recovery

The evaporator is a critical component when using organic Rankine cycle (ORC) to recover waste heat from an internal combustion engine. Evaluating the amount of heat quantity that can be transferred in a designed evaporator is very important for a successful ORC system. In this paper, a finned tube evaporator used for recovering the exhaust waste heat of a diesel engine was presented. The mathematical model for the evaporator was set up according to the dimensions of the designed evaporator along with the specified working conditions of ORC. The evaporator performance was analyzed as the matched diesel engine operating at the rated power point. The results indicate that the heat transfer quantity of the designed evaporator can be reached at 76 kW, and the exhaust temperature at the evaporator exit can be reduced to 115°C.

Effect of Hydrogen Addition into Methane-Air Mixture on Combustion Pressure

To get the effect of hydrogen addition under different initial pressures, different initial temperatures and different initial equivalence ratios on combustion pressure, relevant tests of methane-hydrogen-air mixture have been carried out in constant volume combustion bomb. The results showed that higher initial temperature and lower initial pressure is helpful to get higher flame propagation velocity while other initial conditions keep invariable; as hydrogen blend ratio increases, both maximum combustion pressure and maximum rate of pressure rise increase, with the appearance time obviously earlier and cycle-to-cycle variation obviously lower.

Experimental Study on the Performance of a Natural Gas Engine

Power performance tests of natural gas engine were carried out using a self-dependent developed electronic injection system and ignition system, and a comparative analysis between the natural gas engine and original gasoline engine was conducted. The result shows that if the gasoline engine is fueled with NG torque of the engine decreases and with the throttle opening increases, the decrease amplitude increases. Developing a suitable electronic ignition system can recover engine torque to some extent. Under the conditions that both throttle opening and rotation speed of the engine are constant, MBT angle increases with the decrease of mixture concentration.

Study and Selection of Working Fluids for Organic Rankine Cycle (ORC) Using Engine Waste Heat Energy

In this paper, a basic ORC system is proposed to recover the exhaust gas energy of vehicle engines, and the mathematical model of the ORC system is built. Thirteen working fluids are analyzed. The main criterion for selecting working fluids is the mass flow rate and the heat absorption rate under the same power output of single-screw expander. Then, the paper presents an analysis of the irreversibility rate and thermal efficiency of the ORC system using 4 different organic working fluids.

Effects of Spark Advance Angle on Combustion and Emission Characteristics of a Compressed Natural Gas Engine

The effects of spark advance angle on combustion and emission characteristics of a compressed natural gas engine have been investigated experimentally in this paper. The experimental data was conducted under various excessive air coefficient conditions using an electronic ignition system developed self-dependently. The results show that the peak cylinder pressure and peak rate of pressure rise ascends with the increase of spark advance angle in a certain extent, and their corresponding location are advanced. The CO emission keeps almost the same as the spark advance angle varies in the overall mode range. The HC and NOx emissions ascend with the increase of spark advance angle under the condition that excessive air coefficient is near the theoretical value. Under the lean-burn condition, the HC and NOx emissions are almost the same while the spark advance angle varies.