Exhaust Gas Heat Recovery

In February 2016, the new Hybrid Chevrolet Malibu is launched on the US market. Among the celebrated innovations on the vehicle is EGHRS by BOSAL - the first downstream heat exchange system on the market.


Industry Challanges

The need to reduce CO2 emissions has led to significant improvements in passenger vehicles over the past decade. With engine optimisation and aerodynam­ics now starting to reach their limits, the focus is shifting towards the recovery of thermal energy.
During engine warm-up, efficiency is very low, so faster warming of the internal combustion engine can greatly increase engine fuel efficiency.

BOSAL Solution

BOSAL tackles this by recovering up to 75% of the engine exhaust thermal energy which would otherwise be lost. This thermal energy is used to rapidly heat up the engine at cold start. This eliminates the need for any external electrical, mechanical or thermal energy source. The modular design of the system can be used across car platforms and various engines. The system brings substantial fuel cost savings for the end user, while also delivering significant CO2 reduction.
In addition, faster window defogging and heating of the vehicle cabin help to improve passenger safety and comfort.

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The objective of this system is to recover waste heat of the exhaust gas to heat up the engine coolant, with minimal impact on back pressure and packaging space.

Design Concept

A unique feature of BOSAL’s design is the close coupled location of the unit, which results in maximal energy recovery. The overall design is very compact and only slightly bigger than the pipe diameter.

Double valve

The exhaust gas heat recovery system consists of 2 parallel flow paths, which are regulated by a double valve, providing 2 modes of operation: heat recovery and bypass. In heat recovery mode, the exhaust gas passes through the heat exchanger, which then recovers the thermal energy and transfers it to the engine coolant. In bypass mode, the exhaust gasses flow through the bypass and no heat is recuperated. Careful tuning of the dual valve design results in extremely low parasitic heat.

Double valve design for exhaust heat recovery system

Heat exchanger core

The functional component of the system - the heat exchange core - is composed of a patented plate design with a high rate of effectiveness - up to 75%. The modular sys­tem design allows stacking of the plates in lower or higher quantities to accommodate engine requirements, with minimal further design changes to the system.

BOSAL patented heat exchanger core - Exhaust Gas Heat Recovery System (EGHRS)

Bosal’s design features and benefits

  • Worldwide first production of close coupled Exhaust Gas Heat Recovery system focusing on maximum fuel con­sumption reduction.
  • engine heat-up within 2 minutes using exhaust heat energy
  • Improved engine efficiency at cold start, reducing CO2 and toxic emissions.
  • Greater customer comfort thanks to extremely fast passenger compartment heating.
  • Greater safety thanks to fast window defrosting.
  • Proven 4% reduction of fuel con­sumption on FTP combined cycle and up to 10% fuel consumption reduction under cold climate conditions.
  • Compact design, enabling easier engine integration.
  • Operating temperature up to 850°C with exertion of 1050°C