Knowledge base
A gas engine generator turns around 40 % of its fuel into electricity. Most of the rest is heat, and a combined heat and power (CHP) plant puts that heat to work - in a district heating network, a greenhouse, a hospital, a factory process. Recovering it raises the overall fuel use to 80-90 %, which is why CHP is the standard for gas engines wherever there is a heat consumer. This guide explains where the heat comes from, how it is recovered, and why every CHP plant still needs a radiator.
Where The Heat Comes From
Four sources carry the heat of a gas engine. The jacket water, at 80-95 °C, carries the heat of the cylinders. The lubricating oil carries the heat of bearings and pistons, usually into the jacket water through an oil cooler. The charge air, compressed by the turbocharger, is cooled in two stages: the first, hot stage can feed the heat-recovery circuit, the second, low-temperature stage must be cooled close to ambient for the engine's rating and emissions. The exhaust, at 400-500 °C, carries the largest single share and is recovered in an exhaust gas heat exchanger or a steam boiler.
Roughly, an engine delivers similar amounts of electrical power and recoverable heat; the engine maker's heat balance gives the exact split per circuit and temperature level.
The Heating Module
The heating module is the skid that collects that heat and hands it to the consumer. It carries the plate heat exchanger that separates the engine circuit from the heating network, the pumps, the three-way valves that hold the engine return temperature where the engine maker wants it whatever the network does, the expansion and safety equipment, and the connection to the exhaust heat exchanger. Built as one factory-tested module, it arrives with the pipework, instrumentation and controls in place and reduces site work to a few connections.
Why A CHP Plant Still Needs A Radiator
The heat consumer does not always want the heat: a district heating network in summer, a greenhouse at night, a factory on a holiday. The engine, however, must keep its jacket water and its oil within limits whenever it runs. The emergency cooler - also called a dump radiator - takes over the heat the consumer cannot take, so the engine can keep producing electricity. It is sized for the full engine heat at the summer design ambient, controlled by the same valves that serve the heating module, and usually works only part of the year.
The low-temperature charge-air circuit is a different case: its heat is too cold to be useful in most networks, so it always goes to a radiator - often an LT/HT unit where one coil cools the charge air and the other serves as the emergency cooler. TECS designs and builds heating modules, emergency coolers and LT/HT radiators for gas engine CHP plants as one coordinated system; send the engine heat balance and the network data, and the proposal shows the circuits that fit.
In Short
- Jacket water, oil, charge air and exhaust carry the engine heat
- CHP raises the overall fuel use to 80-90 %
- The heating module separates the engine circuit and controls the return temperature
- The emergency cooler takes the heat the consumer cannot take
- The low-temperature charge-air heat goes to a radiator all year
- TECS builds heating modules, emergency coolers and LT/HT radiators for CHP
What To Send With An Enquiry
- Engine make, model and the heat balance per circuit
- Heating network: supply and return temperatures, flow, pressure
- Whether the exhaust heat is recovered and how
- Site ambient for the emergency cooler and the LT radiator
- Space for the module and the radiators, sound limit
- Control interface with the engine and the network
Questions We Are Often Asked
How much heat can be recovered from a gas engine?
Roughly as much as the electrical output, from jacket water, oil and exhaust together; the engine maker's heat balance gives the figure per circuit. The low-temperature charge-air heat is usually not recovered.
What is an emergency cooler?
A radiator that rejects the engine heat when the heat consumer cannot take it, so the engine can keep running. It is also called a dump radiator or dump cooler.
Why is the engine return temperature controlled?
The engine maker sets a range for the jacket-water return; too cold causes condensation and wear, too hot trips the engine. The heating module's valves hold it there whatever the network does.
Can one radiator do both the emergency and the LT duty?
Yes: an LT/HT radiator carries the charge-air coil and the emergency coil in one casing under one row of fans, each with its own circuit.
Is the heating module part of the engine package?
Sometimes; often it is supplied separately and designed for the specific network. TECS builds it as a factory-tested skid together with the radiators.
Contact Us
Send us the heat duty, the fluid temperatures and flow rates, the ambient conditions and the installation limits. We answer with a design proposal - or write to us on WhatsApp.
