Engines are widely used to generate electricity in places where a reliable power supply is needed. They can operate in remote locations, provide backup power for critical facilities, and support industrial and commercial applications.
But generating electricity is not the only thing an engine produces. A significant amount of energy is released as heat during operation.
In a conventional generator system, much of this heat is simply removed through the cooling system. In a Combined Heat and Power (CHP) system, however, that same heat can be recovered and put to work.
This simple difference can have a major impact on overall energy efficiency.
What Are Engines and CHP Systems?
Engine-based power systems use an internal combustion engine to convert the chemical energy of fuel into mechanical energy. A generator then converts that mechanical energy into electricity.
The process also produces heat from several parts of the engine, including the cooling circuit, lubricating oil, and exhaust gases.
A conventional system usually focuses on removing this heat to keep the engine operating safely. A CHP system takes a different approach: instead of treating the heat only as waste, it recovers as much useful thermal energy as possible.
This is the basic idea behind Combined Heat and Power.
A CHP system can therefore produce:
Electricity + Useful Heat
from the same fuel source.
Why Is Heat Produced by an Engine?
An internal combustion engine cannot convert all the energy in its fuel into electricity.
Part of the energy becomes mechanical power, while another portion leaves the system as heat.
This heat can be found in different areas of the engine:
- Engine cooling water
- Lubricating oil
- Exhaust gases
- Other hot engine components
In a conventional power generation system, this thermal energy may be transferred to the environment through radiators, cooling towers, or other cooling equipment.
That means additional energy can be required simply to get rid of heat that could potentially be useful.
CHP changes this approach by recovering part of that thermal energy.
How Does Combined Heat and Power Work?
The concept behind CHP systems is easier to understand with a simple example.
Imagine a generator producing electricity for a factory. While the engine is running, its cooling water becomes hot.
Instead of sending this hot water directly to a cooling system and losing its thermal energy, a heat exchanger can transfer that heat to another water circuit.
The heated water can then be used for:
- Space heating
- Hot water production
- Industrial processes
- Greenhouse heating
- Heating required within the energy production process
The exact application depends on where the CHP system is installed.
The important point is that the heat is no longer treated as something that simply needs to be removed.
Why Is Heat Recovery Important?
The biggest advantage of CHP is better use of the energy contained in the fuel.
A generator that only produces electricity may leave a considerable amount of useful thermal energy unused. A CHP system can recover part of that energy and use it for another purpose.
This can increase the total energy efficiency of the installation and reduce the amount of additional fuel needed for heating.
For businesses that need both electricity and heat, this can make CHP particularly attractive.
Instead of operating separate systems for power generation and heating, one integrated system can provide both.
The Role of Heat Exchangers in CHP Systems
Heat exchangers are at the center of the heat recovery process.
Their job is to transfer thermal energy from a hot medium to another fluid without directly mixing the two streams.
In an engine-based CHP system, different heat sources may require different heat transfer arrangements.
Jacket Water Cooling
The engine’s cooling water, often referred to as jacket water, absorbs heat from the engine during operation.
A heat exchanger can transfer this thermal energy to a separate water circuit, producing hot water that can be used elsewhere.
This is one of the most common heat recovery applications in engine-based systems.
Oil Cooling
Engine oil also becomes hot during operation and needs to remain within an appropriate temperature range.
A heat exchanger can help control oil temperature while transferring some of its thermal energy to another circuit.
This means the same component can contribute to both engine cooling and energy recovery, depending on the system design.
Exhaust Gas Heat Recovery
Exhaust gases leave an engine at a high temperature and contain significant thermal energy.
Instead of allowing all of this energy to escape, specialized heat recovery equipment can be used to capture part of it.
The recovered heat can then be used to produce hot water or support other thermal processes.
Exhaust gas recovery can be technically more demanding because of the high temperatures and the composition of the exhaust stream, so material selection and system design are particularly important.
CHP Applications
CHP can be used wherever there is a simultaneous demand for electricity and useful heat.
Common applications include:
- Industrial facilities
- Agricultural sites
- Greenhouses
- Hospitals
- Hotels and commercial buildings
- District heating systems
- Biogas power plants
- Remote power installations
One interesting example is a biogas-powered CHP system.
Biogas can be used as fuel for an engine generator to produce electricity. The heat recovered from the engine can then be returned to the biogas process or used for heating elsewhere on the site.
This creates a useful connection between renewable fuel production, electricity generation, and heat recovery.
CHP and Biogas
Biogas is particularly well suited to CHP because the process that produces biogas can also require thermal energy.
For example, anaerobic digestion systems often need controlled temperatures to maintain the biological process.
A biogas CHP unit can produce electricity while recovering heat from the engine. Part of that heat can then be used to maintain the required temperature of the digestion process.
This helps the facility make better use of the energy contained in the biogas rather than using separate energy sources for heating.
The same principle can be applied in agricultural facilities, where recovered heat may also be used for buildings or greenhouses.
What Should Be Considered When Selecting a CHP Heat Exchanger?
Choosing a heat exchanger for engines is not simply a matter of selecting a unit with a suitable heat transfer capacity.
The operating environment also needs to be considered.
Important factors include:
- Engine power and heat output
- Fluid type and composition
- Operating temperature
- Operating pressure
- Required flow rate
- Allowable pressure drop
- Vibration
- Corrosion resistance
- Available installation space
- Maintenance requirements
Vibration deserves particular attention in engine applications. Unlike many stationary thermal systems, engines generate continuous mechanical movement and vibration.
The heat exchanger and its connections therefore need to be suitable for the actual operating environment.
Compact designs can also be valuable where installation space is limited. A smaller heat exchanger can simplify installation and reduce the amount of piping required around the system.
Why Proper Thermal Management Matters
The purpose of cooling is not simply to make the engine colder.
The engine, oil, cooling water, and other components each have their own suitable operating temperature ranges. If temperatures are too high, components can suffer from excessive thermal stress or accelerated degradation. If they are too low, efficiency and operating performance can also be affected.
A well-designed thermal management system keeps these temperatures under control while making useful heat available to other parts of the facility.
This balance between cooling and heat recovery is what makes thermal design so important in modern CHP installations.
AITCO Solutions for Engines and CHP
Every engine and CHP project has different requirements. The engine type, fuel, power output, cooling circuit, heat demand, and available installation space can all affect the appropriate heat exchanger solution.
AITCO helps customers evaluate these conditions and select suitable heat transfer solutions for their applications.
Depending on the project, AITCO can support applications such as:
- Engine cooling
- Jacket water cooling
- Oil cooling
- Heat recovery
- CHP systems
- Biogas engine applications
- Industrial power generation
The selection process can take into account operating temperature, pressure, flow rate, fluid properties, required heat transfer capacity, pressure drop, and installation limitations.
Rather than treating the heat exchanger as an isolated component, AITCO looks at how it needs to perform within the complete system.
Making Better Use of Engine Energy
Engines will continue to play an important role in power generation, particularly where reliable electricity and flexible fuel options are required.
At the same time, improving efficiency means looking beyond electricity production alone.
CHP provides a practical way to recover useful thermal energy that would otherwise be lost. With properly designed heat recovery and cooling systems, the same fuel can provide both electrical power and useful heat.
For facilities that already need both, this can make a significant difference to overall energy utilization.
AITCO supports these systems by helping customers identify heat exchanger solutions that match the technical requirements of their engines, CHP units, and heat recovery applications.
