Automotive Waste Heat Recovery after Engine Shutoff in Parking Lots 2019-01-0157
The efficiency of internal combustion engines remains a research challenge given the thermodynamic and mechanical friction losses. Although incremental engine design changes continue to emerge, the harvesting of waste heat represents an immediate opportunity to address improved energy utilization. An external mobile thermal recovery system for gasoline and diesel engines is proposed for use in parking lots based on phase change material (PCM) cartridges. Heat is extracted via a retrofitted conduction plate beneath the engine block after engine shutoff. An autonomous robot attaches the cartridge to the plate and transfers the heat from the block to the PCM and returns later to retrieve the packet. These reusable cartridges are then driven to a heat extraction and recycling tower (HEART) where a heat exchanger harvests the stored thermal energy. A series of mathematical models and numerical simulations are created to estimate the recoverable heat from a standard parking lot configuration. A representative case study considering 500 vehicles with periodic traffic flow shows a maximum of 421 kWh of energy can be recovered that is sufficient to heat 25,000 liters of water from 15C to 49C. Future development will involve methods to extract heat during engine idling at traffic stops and drive through lanes.