Internal Combustion Engines have much to offer the Hydrogen fuelled future – perhaps as much as fuel cells do. But this isn’t without challenge. Bowman’s Performance Engineering Director, Keith Douglas, outlines some key issues and how eTurbo Systems can be an enabler for success.
Using Hydrogen in internal combustion engines (ICEs) offers a fantastic opportunity for clean (or at least very, very nearly clean*) production of power for electricity generation and direct mechanical applications. ICEs are low cost, mature and ubiquitous – offering a very low risk pathway for using Hydrogen (and other net zero fuels). Furthermore, we have enormous global infrastructure and supply chains to support ICE production, maintenance, application and support, where the carbon cost of setting it all up is already sunk. Continuing ICE use as an alternative, or at least to reduce the need to build out new facilities and infrastructure to for new technologies, is an important option to be weighed up.
ICE OEM’s are working on solving the combustion challenges that currently limit high-speed spark ignited hydrogen ICEs (SI H2 ICE) load capability. Existing examples are capable of about 60% of the power output for a given ICE model compared to the Natural Gas (NG) equivalent. At Bowman, we are working on solutions to support the delivery of the vast quantities of air required to enable increased power densities and on methods to deliver that air rapidly.
Depending on the fuel injection system design and extent of mixing achieved between the hydrogen and air and NOx emissions level required, air-fuel ratios (lambdas) within the range 2.5 and 4 are being evaluated. These extremely high air requirements, compared to NG ICEs, go alongside exhaust temperatures after the ICE turbocharger of between 350 to 300°C, which are very low compared to NG ICEs.
Managing this balance with the turbocharging system is extremely challenging. Compared to typical lean burn SI NG ICE’s in the market today, roughly 1.5 to 2.0 times as much air is required to be delivered to the cylinders by the turbocharger compressor with approximately 100°C less turbocharger turbine inlet temperature – i.e. less power available to the turbocharger turbine.
Bowman’s eTurbocharger technology can supplement the turbine power recovered from the exhaust gas, by continuously adding electrical torque directly to the turbocharger shaft to drive the eTurbocharger’s compressor to higher flow and pressure ratio. Whether it is a single-stage eTurbocharger delivering lambda 2.5, or a 2-stage eTurbocharging system delivering lambda 4, the air delivery requirements for SI H2 ICE’s at the power densities equivalent to today’s NG versions can be achieved without adversely affecting the cylinder scavenging process, which is critical to the hydrogen combustion process.
Additionally, SI H2 ICE combustion has a relatively small operating window requiring tight lambda control throughout the load range. Opportunities to use fuel enrichment to enhance transient response is thus also constrained, further exacerbating the need to deliver more air with less exhaust energy to the extent that highly variable load applications, such as in vehicles, construction machinery, ships and boats etc. have very limited viability.
Bowman’s TorqIQ™ technology allows switching from full electrical motoring torque to full electrical generating torque (and vice versa) to be executed in milliseconds within the eTurbocharger, ensuring precise boost pressure control, delivering the exact amount of air to the cylinders at exactly the right time to enable stable combustion. This new degree of freedom for boost pressure control enables fuelling to be rapidly increased or decreased while maintaining tight lambda control during any transient manoeuvre meaning SI H2 ICE’s will be able to deliver the transient performance we are used to with today’s fossil fuel equivalents.
We are working very hard to be ready for the next phase of SI H2 ICE development.
*ICEs burning hydrogen still need lubricating, and some oil does get burned in the process.
Internal Combustion Engines have much to offer the Hydrogen fuelled future – perhaps as much as fuel cells do. But this isn’t without challenge. Bowman’s Performance Engineering Director, Keith Douglas, outlines some key issues and how eTurbo Systems can be an enabler for success.
Using Hydrogen in internal combustion engines (ICEs) offers a fantastic opportunity for clean (or at least very, very nearly clean*) production of power for electricity generation and direct mechanical applications. ICEs are low cost, mature and ubiquitous – offering a very low risk pathway for using Hydrogen (and other net zero fuels). Furthermore, we have enormous global infrastructure and supply chains to support ICE production, maintenance, application and support, where the carbon cost of setting it all up is already sunk. Continuing ICE use as an alternative, or at least to reduce the need to build out new facilities and infrastructure to for new technologies, is an important option to be weighed up.
ICE OEM’s are working on solving the combustion challenges that currently limit high-speed spark ignited hydrogen ICEs (SI H2 ICE) load capability. Existing examples are capable of about 60% of the power output for a given ICE model compared to the Natural Gas (NG) equivalent. At Bowman, we are working on solutions to support the delivery of the vast quantities of air required to enable increased power densities and on methods to deliver that air rapidly.
Depending on the fuel injection system design and extent of mixing achieved between the hydrogen and air and NOx emissions level required, air-fuel ratios (lambdas) within the range 2.5 and 4 are being evaluated. These extremely high air requirements, compared to NG ICEs, go alongside exhaust temperatures after the ICE turbocharger of between 350 to 300°C, which are very low compared to NG ICEs.
Managing this balance with the turbocharging system is extremely challenging. Compared to typical lean burn SI NG ICE’s in the market today, roughly 1.5 to 2.0 times as much air is required to be delivered to the cylinders by the turbocharger compressor with approximately 100°C less turbocharger turbine inlet temperature – i.e. less power available to the turbocharger turbine.
Bowman’s eTurbocharger technology can supplement the turbine power recovered from the exhaust gas, by continuously adding electrical torque directly to the turbocharger shaft to drive the eTurbocharger’s compressor to higher flow and pressure ratio. Whether it is a single-stage eTurbocharger delivering lambda 2.5, or a 2-stage eTurbocharging system delivering lambda 4, the air delivery requirements for SI H2 ICE’s at the power densities equivalent to today’s NG versions can be achieved without adversely affecting the cylinder scavenging process, which is critical to the hydrogen combustion process.
Additionally, SI H2 ICE combustion has a relatively small operating window requiring tight lambda control throughout the load range. Opportunities to use fuel enrichment to enhance transient response is thus also constrained, further exacerbating the need to deliver more air with less exhaust energy to the extent that highly variable load applications, such as in vehicles, construction machinery, ships and boats etc. have very limited viability.
Bowman’s TorqIQ™ technology allows switching from full electrical motoring torque to full electrical generating torque (and vice versa) to be executed in milliseconds within the eTurbocharger, ensuring precise boost pressure control, delivering the exact amount of air to the cylinders at exactly the right time to enable stable combustion. This new degree of freedom for boost pressure control enables fuelling to be rapidly increased or decreased while maintaining tight lambda control during any transient manoeuvre meaning SI H2 ICE’s will be able to deliver the transient performance we are used to with today’s fossil fuel equivalents.
We are working very hard to be ready for the next phase of SI H2 ICE development.
*ICEs burning hydrogen still need lubricating, and some oil does get burned in the process.
Internal Combustion Engines have much to offer the Hydrogen fuelled future – perhaps as much as fuel cells do. But this isn’t without challenge. Bowman’s Performance Engineering Director, Keith Douglas, outlines some key issues and how eTurbo Systems can be an enabler for success.
Using Hydrogen in internal combustion engines (ICEs) offers a fantastic opportunity for clean (or at least very, very nearly clean*) production of power for electricity generation and direct mechanical applications. ICEs are low cost, mature and ubiquitous – offering a very low risk pathway for using Hydrogen (and other net zero fuels). Furthermore, we have enormous global infrastructure and supply chains to support ICE production, maintenance, application and support, where the carbon cost of setting it all up is already sunk. Continuing ICE use as an alternative, or at least to reduce the need to build out new facilities and infrastructure to for new technologies, is an important option to be weighed up.
ICE OEM’s are working on solving the combustion challenges that currently limit high-speed spark ignited hydrogen ICEs (SI H2 ICE) load capability. Existing examples are capable of about 60% of the power output for a given ICE model compared to the Natural Gas (NG) equivalent. At Bowman, we are working on solutions to support the delivery of the vast quantities of air required to enable increased power densities and on methods to deliver that air rapidly.
Depending on the fuel injection system design and extent of mixing achieved between the hydrogen and air and NOx emissions level required, air-fuel ratios (lambdas) within the range 2.5 and 4 are being evaluated. These extremely high air requirements, compared to NG ICEs, go alongside exhaust temperatures after the ICE turbocharger of between 350 to 300°C, which are very low compared to NG ICEs.
Managing this balance with the turbocharging system is extremely challenging. Compared to typical lean burn SI NG ICE’s in the market today, roughly 1.5 to 2.0 times as much air is required to be delivered to the cylinders by the turbocharger compressor with approximately 100°C less turbocharger turbine inlet temperature – i.e. less power available to the turbocharger turbine.
Bowman’s eTurbocharger technology can supplement the turbine power recovered from the exhaust gas, by continuously adding electrical torque directly to the turbocharger shaft to drive the eTurbocharger’s compressor to higher flow and pressure ratio. Whether it is a single-stage eTurbocharger delivering lambda 2.5, or a 2-stage eTurbocharging system delivering lambda 4, the air delivery requirements for SI H2 ICE’s at the power densities equivalent to today’s NG versions can be achieved without adversely affecting the cylinder scavenging process, which is critical to the hydrogen combustion process.
Additionally, SI H2 ICE combustion has a relatively small operating window requiring tight lambda control throughout the load range. Opportunities to use fuel enrichment to enhance transient response is thus also constrained, further exacerbating the need to deliver more air with less exhaust energy to the extent that highly variable load applications, such as in vehicles, construction machinery, ships and boats etc. have very limited viability.
Bowman’s TorqIQ™ technology allows switching from full electrical motoring torque to full electrical generating torque (and vice versa) to be executed in milliseconds within the eTurbocharger, ensuring precise boost pressure control, delivering the exact amount of air to the cylinders at exactly the right time to enable stable combustion. This new degree of freedom for boost pressure control enables fuelling to be rapidly increased or decreased while maintaining tight lambda control during any transient manoeuvre meaning SI H2 ICE’s will be able to deliver the transient performance we are used to with today’s fossil fuel equivalents.
We are working very hard to be ready for the next phase of SI H2 ICE development.
*ICEs burning hydrogen still need lubricating, and some oil does get burned in the process.