Guys (and Gals),
I am posting
this in order to lay to rest some of the confusion about Free-Piston Stirling Coolers (FPSC) based equipment
(including the Coleman Stirling Power Cooler).
- The Coleman unit is a re-branded (part# SC-C925) unit manufactured by a company named Twinbird in Japan
(using technology licensed from Global Cooling) and their products are distributed outside of Japan
and SE Asia
by Global Cooling The .nl site has not been updated yet this year so use the .com address
- The Coleman unit uses a small 40W FPSC to pump heat
- Coleman uses a CO2 based thermosiphon (read: Gravity driven heat pipe) to pump heat from the cold chamber
- The 12 deg restriction (a very conservative number by the way) is based on the nature of the thermosiphon and in truth is only appropriate in a very limited number of orientations. In some orientations it can happily operate at >90 deg from horizontal. All of this is really moot anyway because it refers to CONTINUOUS operation at a specific angle. (if your boat is listing at a constant angle of more that 12 deg you've got bigger problems than refrigeration). Under sail you basically just need to make sure that the cooling unit (under the large gray cover) is the system high point. If you regularly cruise
at high angle of attacks, there are convective systems, using the same technology, that are completely independent of orientation (SC-JS04 and SC-JS05).
- Availability of the Coleman branded unit is dropping but Twinbird branded units are still freely available from Global Cooling.
- 48W of power consumption
is max cold setting in max ambient temperature. In most refrigeration circumstances power draw is 10W to 20W. To freeze it will take 20-48W depending on which freeze setting is used and how hot it is outside. Incidentally, the Coleman unit has no difficulty keeping its cold chamber 0 deg F (Freeze 2) in ambient temperatures well above 100 deg F.
- As alluded to earlier, the Coleman unit is only ONE of the portable refrigerator/freezers available using FPSC technology
- Prices range from ~$400 to ~$25,000 (you probably don't need something this expensive but if you want it we've got 'em.
- We'll sell one (FPSC, Portable refrigerator/Freezer), to anyone who agrees, in writing, to abide by US Export law.
- Have (typically) 2 moving internal components and one external moving component
- Do NOT have any internal oil
(oil would destroy its performance)
- Some units use active gas bearings to isolate internal moving components but not all (it's a cost thing). Units without active gas bearings rely on fluid dynamic forces created by component geometry and clearances to isolate moving components and advanced dry bearing systems. Twinbird warranties their products for 1 year but I personally have been running one of the Coleman boxes for 3 years continuously in a, with no measurable performance degradation.
- COP's (pumped heat/input power) range from 1.2 to 4 depending on model
- Are able to modulate their capacity almost instantly and to any capacity from 0% to 100%, without sacrificing efficiency. In essence, they only use as much power as is necessary to maintain a set temperature and no more!
- Have extremely long life expectancies (some well over 100,000 hours)
3. Available units
-SC-C925 ~48W max consumption (same as Coleman)
-SC-DF25 ~48W max consumption (same form factor as Coleman w VIP insulation -40 deg capable in single
-SC-BV25 or WH25 ~25W (single temp setting (4 deg C) for blood/vaccine/organ transport)
-SC-JS04 ~50W max consumption (self contained refrigeration unit simply add an insulated container like a built in ice box or a typical ice chest, single
temperature setting (4 deg C), Convective transfer (fans instead of a thermosiphon so will happily run in any orientation), refrigerate up to 8 cu.ft. with 2 inches of foam insulation)
-SC-JS05 ~80W max consumption (high capacity version of JS04 with 3 temp settings (4,-18,-35 deg C,-35 only achievable up to 4 cu.ft. with 2 inches of foam insulation but come on, that's seriously cold!)
-SC-UL25 ~130W max consumption (same form factor as DF25 but capable of -92 deg C (really, really seriously cold)
-Various stand alone FPSC's ranging from 40W to 150W capacity