The fast reduction of fossil fuels is making it imperative to search for renewable fuels to be used in the IC engines. The use of alcohols as fuel in the CI engines either directly or as blends of diesel requires some modification of the engine operating parameters to minimize the emissions without affecting the performance. Among the different operating parameters, Compression ratio (CR) and Fuel injection pressure (FIP) strongly affect the performance characteristics of the CI engine. In this paper, the influence of CR and FIP on the combustion, performance and emission characteristics of a CI engine fuelled with butanol/diesel (B/D) blends is presented. Experiments were performed on a Variable Compression Ratio (VCR) engine by varying the CR (CRs of 14:1, 15:1, 16:1, 17.5:1and 18:1) and the FIP (FIP of 200 bar, 220 bar, 240 bar, 260 bar and 280 bar) with three different (B/D) blends (butanol fraction of 0%, 20% and 40% by volume). The experimental outcomes showed that for all the (B/D) blends, with increase in the CR from 14 to 18, the in-cylinder pressure, net heat release (NHR) and Brake Thermal Efficiency (BTE) increased. The soot, CO and UBHC emissions decreased, while the NOx emissions increased with increase in the CR from 14 to 18. Similarly, the effect of FIP was to increase the in-cylinder pressure, net heat release (NHR), BTE and the NOx, and reduce the soot CO and UBHC emissions. The effect of CR and FIP for different butanol/diesel blends was experimentally evaluated. There existed an optimum value of FIP for each test fuel, corresponding to which the best performance was obtained. For the Bu00 (diesel) and Bu20 test fuels this optimum value was 260 bar, whereas for the Bu40 test fuel, it was 240 bar. At the higher CR of 18, Bu40 gave the best performance with BTE of 30.14%.

化石燃料的快速减少使得必须寻找可用于IC发动机的可再生燃料。在CI发动机中直接或以柴油的混合物形式使用醇作为燃料，需要对发动机的运行参数进行一些修改，以在不影响性能的情况下将排放降至最低。在不同的运行参数中，压缩比（CR）和燃油喷射压力（FIP）强烈影响CI发动机的性能特征。本文介绍了CR和FIP对以丁醇/柴油（B / D）混合物为燃料的CI发动机的燃烧，性能和排放特性的影响。通过更改CR（CR为14：1、15：1、16：1、17.5：1和18：1）和FIP（FIP为200 bar，220 bar， 240巴 260 bar和280 bar）与三种不同的（B / D）混合物（丁醇含量分别为0％，20％和40％）。实验结果表明，对于所有（B / D）混合物，CR均从14增加到18，缸内压力，净热释放（NHR）和制动热效率（BTE）均增加。烟灰，CO和UBHC排放量减少，而NOx排放量随着CR的增加而从14增加到18。同样，FIP的作用是增加缸内压力，净热释放（NHR），BTE和NOx ，并减少烟尘中的CO和UBHC排放。实验评估了CR和FIP对不同丁醇/柴油混合物的影响。每个测试燃料都有一个最佳的FIP值，与之相对应的是获得了最佳性能。对于Bu00（柴油）和Bu20试验燃料，该最佳值为260 bar，而Bu40测试燃料为240巴。在18的较高CR时，Bu40以30.14％的BTE表现最佳。