Salvo wrote:
Are you the man to see about gen packaging? Do you advise using a fan? Or a full enclosure? I've operated the gen in this configuration for a duration of 2 years now.
Thanks,
Sal
IMHO, from an engineering approach, Brad has completed the best thought out and designed enclosure for use in a confined space to:
- reduce noise
- reduce vibration
- effectively divert exhaust gases
- safely remote the fuel tank
- provide normal operating temps of engine and electronics
- allow access for normal service and maintenance
- insulate surrounding walls and objects from engine heat conduction
He is sometimes a little modest on his accomplishments ๐
The issue of cooling or adequate air circulation is much easier to accomplish and less of an engineering challenge. I did a series of tests several years back that led me to these conclusions. While these are specific to the 3,000 watt class of open frame generators, much is applicable to other designs and frames.
Key to the whole thing is to keep the air exiting the cooling part of the generator and engine less than 160 degrees F.(exclusive of exhaust temperatures). The 160 degree limit was derived by the apparent breakdown temp of the AVR and the wiring insulation used in the open frame class of Chinese 3,000 watt generators. The absolute maximum temperature allowable in such an environment is 190 degrees F. The 160 degree measurement point was in the air channel under the connection point of the generator and engine.
When a generator is placed in an enclosed, or semi-enclosed cabinet we have to be sure that it can maintain "normal expected" cooling air flow and exchange without recirculating heated air, heating objects adjacent to the generator that will radiate stored heat (i.e. muffler, etc) back to the cooling air or recirculate heated exhaust gasses.
Key to this is allowing the generator and engine components to receive air to their respective cooling inlet points without any impediments. On the Chinese open frame generators these two points are the engine shroud openings around the recoil starter and the extreme end of the generator housing.
The discharge air points must also be maintained.
On the 3,000 watt class of Chinese generators the major discharge point of cooling air is directly under the generator at the connection of the engine and generator. At this point there is an internal fan for the generator that pulls air into the end housing and out the bottom. An adequate opening at this location must be maintained.
The addition of a fan capable of high air flow and static pressures under the generator at this hot air exhaust point will enhance cooling by sustaining adequate air flow. Such a fan will also remove much of the heated air in the enclosure that is radiated up and outward from the engine.
Heat from the muffler and exhaust pipe can be a major barrier to proper cooling inside an enclosure. Normal cooling of the muffler is by radiation rather than circulation. If designing an enclosure where the muffler is not remote an additional air intake must be added at the top over the muffler and behind the muffler to pull outside cooling air across the large metal surface. These openings should be approximately 2โ in diameter. An enclosure with the muffler intact will need an exhaust fan.
I found that little, if anything is to be gained in a small enclosure by blowing air into the enclosure. In larger enclosures (i.e. back of a pick-up truck camper shell) the use of an open air fan to assist in cabinet air flow may be beneficial.
Photos show cooling air flow patterns on a 3,000 watt open frame Chinese generator that must not be altered or blocked.
