Every generator set turns only part of its fuel energy into electricity. The rest leaves the engine as heat - through the exhaust, the jacket water, the charge air and the lubricating oil - and most of the heat carried by liquid circuits must be rejected to the ambient air by a radiator. When the radiator cannot stand directly in front of the engine, because of noise, space, engine-room temperature or plant layout, a remote radiator takes over that job. This article explains how remote radiators work, why most modern engines need two cooling circuits, and what makes a radiator selection reliable on site.
What A Remote Radiator Does
A remote radiator is a heat exchanger with its own electric fans, installed away from the engine - on the roof, beside the generator hall, on a steel platform or next to a container. The engine's coolant is pumped to the radiator through pipework, gives up its heat to the air drawn or blown through the finned coil, and returns to the engine. Because the fans are driven electrically and not by the engine, their speed can be controlled independently, which allows quieter operation at part load and lower parasitic power.
TECS builds horizontal remote radiators for installations with free space around them, vertical remote radiators for engine rooms and louvred walls, and V-type radiators where many units must share a limited footprint.
Why Engines Have LT And HT Circuits
Large diesel and gas engines usually separate their cooling into two circuits:
- The high-temperature (HT) circuit cools the cylinder jackets and heads - the jacket water. It runs hot, which keeps the engine efficient and makes its heat valuable for recovery.
- The low-temperature (LT) circuit cools the charge air after the turbocharger and often the lubricating oil. Colder charge air means denser air in the cylinders, higher output and, in gas engines, protection against knocking.
An LT/HT radiator carries both circuits in one casing, with separate coils, headers and connections, cooled by the same fans. The air usually passes the LT section first and the HT section second, so the colder circuit sees the coolest air. Designing the two sections together - rather than as two separate coolers - makes better use of the air and of the space.
What Decides A Reliable Selection
A radiator that works on the test bench can still fail in the field if the selection ignores the site. The points that matter most:
- The engine manufacturer's data - heat rejection of each circuit, coolant flow, inlet and outlet temperatures and the allowable pressure drop. The radiator is designed around the engine, not the other way round.
- The real ambient - the hottest air temperature the site will see, the altitude (thinner air carries less heat) and the humidity.
- The coolant - water or a glycol mixture, whose properties change the heat transfer and the pressure drop.
- The installation - nearby walls, other radiators and exhaust outlets can feed warm air back into the intake; ducts and louvres add resistance the fans must overcome.
- The sound limit - a level at a stated distance that shapes the number of fans, their speed and type.
- The atmosphere - coastal, desert, dusty or chemical sites call for suitable fin materials, coatings and casings.
Remote Or Engine-Mounted?
For many generator sets an engine-driven mechanical radiator mounted on the same base frame is the simplest answer. A remote radiator becomes the better choice when the engine room cannot handle the cooling air, when the noise must be kept outside, when several engines are installed side by side, or when the heat should be recovered for heating and only the surplus rejected.
A remote radiator is a small part of a power plant's cost and a large part of its reliability: if it cannot reject the heat on the hottest day, the engine derates or stops. Treating the LT and HT circuits, the site conditions and the installation as one design problem is what keeps generator sets at full output. TECS Engineering designs remote radiators for each project's engine data and site - send us your enquiry.
