对于安全专家而言，网联系统就像是一种取之不尽的馈赠，但随着一些具备网联功能的汽车数量不断增加，相关汽车网络安全隐患的数量随之急剧爆发。此外，一些老款车型的安全漏洞也随之暴露，这也需要进行持续不断的升级。

尽管在真正具备商业价值之前仍需攻克大量挑战，但低温燃烧（LTC）技术已然发展为一种极具价值的热门研究领域。在 WCX17 - SAE 2017年全球汽车年会期间，专家组成员对量产低温燃烧发动机的前景持悲观态度，但仍然看好这种技术在减排方面的潜力。

现阶段，针对低温燃烧技术的研发非常之多，共有29个成员国的国际能源协会（International Energy Assoc.）已经成立了专门的工作组，从事低温燃烧技术方面的研发。来自沃尔沃卡车（Volvo Global Truck）的Arne Andersson也向在场观众介绍了一项针对低温燃烧发动机燃料选择的研究。他表示，这份研究主要涉及7种燃料，其中最适合低温燃烧发动机的是生物柴油、甲烷和乙醇。

德尔福汽车系统（Delphi Automotive Systems）的Mark Sellnau指出，低温燃烧发动机可以提高效率并减少排放，不过他也同时表示火花点火型低温燃烧发动机的收益可能只在10%以下。考虑到目前尚未攻克的多个难题，他建议研究人员专注于对现有燃料的研究。

“低温燃烧发动机的尾气温度更低，这会给尾气处理带来一定困难。”Sellnau表示，“此外，这种发动机也无法提供足够的能量来驱动涡轮工作，压缩点火发动机的实力则相对更强。”

目前，研究人员面临的核心问题仍是找到合适的燃料。美国桑迪亚国家实验室（SandiaNational Laboratories）的Magnus Sjöberg指出，许多燃料并不具备足够的能量，能让动力系统在低温环境下“跑起来”。

此外，专家组成员表示，如果具备更好的开发工具，研发人员的研发过程可能会更加轻松。“我们完全可以利用计算流体动力学（CFD）和化学模型技术进行虚拟测试，从而降低进行现实世界测试的需求。”瑞典隆德大学的Per Tunestal表示，“但现有工具的预测功能不够强、不够快，也不够准确。”

虽然与会专家均认为当下进行的相关研究很值得兴奋，但也坦诚表达了对低温燃烧技术商业化前景的悲观看法。在SAE 2017 全球汽车年会期间，有位参会人员提问要求专家组成员在燃料价格保持相对平稳的前提下，预测未来10年中将采用低温燃烧技术的发动机的比例。

美国阿岗国家实验室的Stephen Ciatti回答说，“0%”。其他两位专家组成员也同意Ciatti的答案。Ciatti表示，种类太多，是低温燃烧技术面临的一大挑战。

“这里并没有什么最佳解决方案，更多取决于你希望系统达到的使用寿命、可用燃料及成本水平等因素。”Ciatti说，“不同的厂商会给出不同的答案，比如瑞典的沃尔沃卡车和美国的乘用车制造商就可能会做出截然不同的选择。”

Low-temperature combustion (LTC) remains an area of high interest with extensive research, even though many challenges must still be overcome before LTC sees commercial acceptance. Though panelists at the SAE WCX 2017 were pessimistic about the prospects for production engines, they remain bullish about the technology’s potential for reducing emissions.

There’s plenty of research going on. The International Energy Assoc., which represents 29 member countries, has dedicated a task force to the technology. Arne Andersson of Volvo Global Truck described an ongoing study into seven fuels used on low temperature engines. Biodiesel, methane and ethanol are preferred, he said.

Delphi Automotive Systems’ Mark Sellnau noted that LTC improves efficiency and reduces emissions, although he said spark ignited engines may only see gains under 10%. He suggested that researchers focus on fuels that are readily available, since there are many other challenges that must be overcome.

“LTC translates to low temperature exhaust, which makes aftertreatment an issue,” Sellnau said. “Also, there’s not much energy to drive a turbo. Compression [ignition] engines are stronger candidates.”

Finding the right fuel remains a central issue for researchers. Magnus Sjöberg of Sandia National Laboratories noted that many fuels don’t have enough energy to “make things happen” at low temperatures. Panelists said that R&D could proceed more quickly if development tools were better.

“One thing we could really use is computational fluid dynamic and chemical models that are actually predictive so we could test virtually instead of only in physical tests,” said Per Tunestal of Sweden’s Lund University. “Tools are not predictive enough, not fast enough and not accurate enough.”

While panelists expressed excitement about ongoing research, they were also honest about predictions for commercial applications. A member of the standing room only audience asked panelists to predict the percentage of engines sold in 10 years that would employ LTC technology, given fairly stable fuel prices.

“Zero,” was the response from Stephen Ciatti of Argonne National Laboratory. Two other panelists concurred with that prediction. Ciatti said diversity is a big challenge for LTC.

“There’s no one best solution. It depends on the level of longevity you want, the type of fuel that’s available, the lowest cost," Ciatti said. "The answers are different for Volvo trucks in Sweden and passenger cars in the U.S."

Author: Terry Costlow
Source: SAE Automotive Engineering Magazine