Performance characteristics of a low heat rejection diesel engine operating with biodiesel

Abstract

Vegetable oils are a promising alternative among the different diesel fuel alternatives. However, the high viscosity, poor volatility and cold flow characteristics of vegetable oils can cause some problems such as injector coking, severe engine deposits, filter gumming, piston ring sticking and thickening of lubrication oil from long-term use in diesel engines. These problems can be eliminated or minimized by transesterification of the vegetable oils to form monoesters. These monoesters are known as biodiesel. The important advantages of biodiesel are lower exhaust gas emissions and its biodegradability and renewability compared with petroleum-based diesel fuel. Although the transesterification improves the fuel properties of vegetable oil, the viscosity and volatility of biodiesel are still worse than that of petroleum diesel fuel. The energy of the biodiesel can be released more efficiently with the concept of low heat rejection (LHR) engine. The aim of this study is to apply LHR engine for improving engine performance when biodiesel is used as an alternative fuel. For this purpose, a turbocharged direct injection (DI) diesel engine was converted to a LHR engine and the effects of biodiesel (produced from sunflower oil) usage in the LHR engine on its performance characteristics have been investigated experimentally. The results showed that specific fuel consumption and the brake thermal efficiency were improved and exhaust gas temperature before the turbine inlet was increased for both fuels in the LHR engine. r

Combustion and performance characteristics of CI (compression ignition) engine running with biodiesel

“…These studies indicate that the fuel consumption is, on average, proportional to the loss of heating values, irrespective of whether heavy-duty or light-duty engines were tested. For example, Hasimoglu et al [37] obtained 13% higher BSFC with a biodiesel having LHV 13.8% lower as compared to diesel on a 4-cylinder, TU and DI diesel engine. [38] found that the BSFC of B100 biodiesel, with a low heating value, 12.9% lower than that of diesel, had increased approximately by 12%, compared to the diesel on a 2.5L, DI and TU, common-rail diesel engine operating at 2400rpm and 64Nm.…”

“…However, to establish blending and physical properties effects, the blended fuels were prepared by mixing ROB and diesel in different proportions using in tank blending method [37]. Blended fuel has percentage volumetric fraction of 0%, 10%, 20%, 50%, 75% and 100% of Biodiesel and named B0, B10, B20, B50, B75 and B100 respectively.…”

Durability test on an agricultural tractor engine fuelled with pure biodiesel (B100)

“…The reason for the decreases in power and torque was the lower calorific value of biodiesel (National Biodiesel Board, 2005;CTI -Comitato Termotecnico Italiano, 2013). The increase in BSFC (Utlu and Koçak, 2008;Aydin and Bayindir, 2010) is the result of both the different lower calorific value of biodiesel (hence, of the engine power) and of biodiesel reduced inclination to evaporate compared to diesel oil (Szybist et al, 2007;Haşimoğlu et al, 2008), which is also the cause behind the longer delays in fuel ignition and the changes in the heat release rate and pressure curves (Xue et al, 2011). Figure 2 shows that a biodiesel-fuelled engine has a smokiness that is approximately half of the diesel-oilfuelled engine throughout its entire operative range, due to the higher oxygen content of biodiesel (Murillo et al, 2007).…”

“…Moreover, the engine thermal efficiency does not change and can even improve slightly (Murillo et al, 2007;Raheman and Ghadge, 2007;Szybist et al, 2007;Haşimoğlu et al, 2008;Nabi et al, 2009;Qi et al, 2009;Ryu, 2010;Aybek et al, 2011); however, engine power is reduced (Özkan et al, 2005;Nabi et al, 2009;Qi et al, 2009;Altun, 2011) due to biodiesel lower calorific value and higher viscosity (Szybist et al, 2007;Haşimoğlu et al, 2008). In fact, the viscosity of biodiesel is extremely high at 25 °C, reaching up to 1.6 times the diesel oil viscosity up to 40 °C (Tesfa et al, 2010).…”

“…Technically speaking, all these effects result in longer delays in fuel ignition (Xue et al, 2011) and change the heat release rate curve, the pressure curve, and the exhaust gas temperature (Utlu and Koçak, 2008;Aydin and Bayindir, 2010;Xue et al, 2011). As a consequence, the brake specific fuel consumption (BSFC) increases (Ramadhas et al, 2004(Ramadhas et al, , 2005Özkan et al, 2005;Haşimoğlu et al, 2008;Altun, 2011), though the smokiness lowers to 50% (Utlu and Koçak, 2008;Qi et al, 2009;Pal et al, 2010;Xue et al, 2011) due to the increased availability of oxygen in the biodiesel, which promotes the combustion process and soot oxidation (Qi et al, 2009;Xue et al, 2011). From a technical point of view, the modifications to engines to be powered by biodiesel are minimal if not absent (Meher et al, 2006;Fazal et al, 2011).…”