Despite being subjected to tight sustainability restrictions in the last decade (Directives 2009-28-CE, 2015-1513-CE, and EU-2018-2001), the use of biodiesel in compression ignition engines is still increasing in the European Union. As known, one of the main drawbacks of biodiesel is cold flow behavior, along with oxidation stability problems. According to European standards, the Cold Filter Plugging Point and Cloud Point methods are the ones used to ensure diesel vehicle operability in temperate and arctic climates, respectively, within the EU. Despite the existing standards, several issues related to startability have occurred in the northern European countries due to filter clogging. In this frame, this study checks the reliability of the conventional Cold Filter Plugging Point and Cloud Point tests by comparing their results with those coming from an experimental rig that simulates the low-pressure fuel circuit of a diesel vehicle. Baseline diesel was blended with two biodiesel fuels (7% and 10% by volume) produced from palm oil. Regardless of the fuel used and the blend (B7 or B10), Cold Filter Plugging Point and Cloud Point methods underestimate the temperature at which the filter clogging occurs compared to real conditions, these differences being as significant as 4°C when compared to Cold Filter Plugging Point and Cloud Point, respectively. Results obtained encourage either searching for more reliable standards to quantify the cold flow behavior of biodiesel fuels or limiting the maximum content of the main compounds causing cold-start problems.

中文翻译：

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冷滤器堵塞点和浊点是否足够可靠以防止使用生物柴油混合物的车辆出现冷启动可操作性问题？

尽管在过去十年中受到严格的可持续性限制（指令 2009-28-CE、2015-1513-CE 和 EU-2018-2001），但生物柴油在压燃式发动机中的使用在欧盟仍在增加。众所周知，生物柴油的主要缺点之一是冷流行为以及氧化稳定性问题。根据欧洲标准，冷过滤器堵塞点和浊点方法分别用于确保欧盟范围内柴油车辆在温带和北极气候下的可操作性。尽管存在现有标准，但由于过滤器堵塞，北欧国家发生了一些与启动性相关的问题。在这个框架中，本研究通过将传统冷滤器堵塞点和浊点测试的结果与来自模拟柴油车低压燃料回路的实验台的结果进行比较，来检查其可靠性。基准柴油与两种由棕榈油生产的生物柴油燃料（按体积计 7% 和 10%）混合。无论使用何种燃料和混合（B7 或 B10），冷过滤器堵塞点和浊点方法与实际条件相比都低估了过滤器堵塞发生的温度，与冷过滤器相比，这些差异高达 4°C分别为堵塞点和浊点。