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.
This paper investigates the effect of ethanol addition and hot exhaust gas recirculation (EGR) on engine performance, exhaust emissions, and air-pollution damage-cost in a dual-fuel diesel engine. The ethanol is injected at low pressure into the intake manifold using a port-fuel injector while diesel fuel is injected directly into the cylinder. Only the duration of the ethanol injection is changed in the dual-fuel injection system while the diesel injection parameters are not changed. Ethanol fuel is added by port injection in such amounts as to provide additional heat energy in the range of 0–40% to the heat energy of the diesel fuel taken to the engine for any engine operating conditions. Moreover, 5%, 10%, and 15% rates exhaust gas recirculation (hot EGR) for each engine operating conditions are applied. The engine is operated at 1400, 1600, 1800 and 2000 rpm engine speeds at full load (≈40 Nm). In this paper, the highest improvement in engine performance and environmental factors is obtained with ethanol addition of 40% without the hot EGR at 1400 rpm. Under these conditions, the brake engine power ( BEP) and brake engine torque ( BET) increase of 6.9% and 8.1% while NOx emission and air-pollution damage-cost decreased of 32% and 23.9%, respectively. However, CO, HC, and smoke ( FSN number) emissions increased significantly. On the other hand, the brake thermal efficiency ( BTE) and brake specific energy consumption ( BSEC) are negatively affected by the ethanol addition and hot EGR.
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