Methods and systems for exhaust gas heat recovery

The invention relates to methods and systems for exhaust gas heat recovery. Methods and systems are provided for exhaust flow in an engine system including a split-exhaust manifold for expediting exhaust catalyst light-off and engine warm-up while reducing condensation in the engine system. In one example, a method may include, before exhaust catalyst light-off, flowing all or more exhaust gases, via a first exhaust valve and a first exhaust manifold, to an exhaust catalyst by passing a heat exchanger. Further, after light-off but before engine coolant warms up to a threshold temperature, all or more exhaust may be delivered to the heat exchanger, via a second exhaust valve and a second different manifold, prior to flowing to the exhaust catalyst; and exhaust gas recirculation may not be provided until the coolant reaches the threshold temperature to reduce condensation. 本申请涉及用于排气热回收的方法和系统。提供了用于包括分流排气歧管的发动机系统中的排气流的方法和系统，用于加速排气催化剂起燃和发动机预热，同时减少发动机系统中的冷凝。在个示例中，方法可包括在排气催化剂起燃之前，使所有或更多排气绕过热交换器经由第排气门和第排气歧管流动到排气催化剂。此