Experimental investigation of an improved exhaust recovery system for liquid petroleum gas fueled spark ignition engine

In this study, we have investigated the recovery of energy lost as waste heat from exhaust gas and engine coolant, using an improved thermoelectric generator (TEG) in a LPG fueled SI engine. For this purpose, we have designed and manufactured a 5-layer heat exchanger from aluminum sheet. Electrical energy generated by the TEG was then used to produce hydrogen in a PEM water electrolyzer. The experiment was conducted at a stoichiometric mixture ratio, 1/2 throttle position and six different engine speeds at 1800-4000 rpm. The results of this study show that the configuration of 5-layer counterflow produce a higher TEG output power than 5-layer parallel flow and 3-layer counterflow. The TEG produced a maximum power of 63.18 W when used in a 5-layer counter flow configuration. This resulted in an improved engine performance, reduced exhaust emission as well as an increased engine speed when LPG fueled SI engine is enriched with hydrogen produced by the PEM electrolyser supported by TEG. Also, the need to use an extra evaporator for the LPG fueled SI engine is eliminated as LPG heat exchangers are added to the fuel line. It can be concluded that an improved exhaust recovery system for automobiles can be developed by incorporating a PEM electrolyser, however at the expense of increasing costs

Theoretıcal Optımızatıon Of The P-N Type Semıconductor Materıal Paır In Thermoelectrıc Generator That Achıevement Exhaust Waste Heat Recovery

In this study, the effect of the use of different p-n type semiconductor materials in the thermoelectric generator designed to convert the exhaust waste heat energy of the internal combustion engines to electrical energy on the output parameters of the thermoelectric generator (load current, output voltage and power under load) is theoretically investigated. In the study, 4 different p-n pairs were formed for p-n pairs, forming thermoelectric modules, consisting of a combination of 4 different semiconductor materials of type Bi2Te3, Bi0.3Sb1.7Te3, PbSe0.5Te0.5 and Zn4Sb3. The thermoelectric generator using thermoelectric modules created from the determined p-n pairs was analyzed using the theoretical thermoelectric generator model developed in the Matlab/Simulink program in the previous study. In the theoretical model, the engine coolant temperature and flow values were used besides the temperature and flow rate of the exhaust gas obtained from experimental studies carried out in the 1500-4000 rpm range of a two-cylinder spark-ignition engine. The findings show that the thermoelectric generator produced the highest power output of the under the electrical load with the thermoelectric modules which is created using the Bi0.3Sb1.7Te3 and Bi2Te3 type semiconductors for the p-n pairs, respectively. Also, using the thermoelectric generator created by connecting twenty thermoelectric modules in series, 86.53 W (output current = 1.073 A and output voltage = 80.64 V) DC electrical power was obtained by the temperature difference of ΔT = 162.4 K at 4000 rpm engine speed