.....question ....are thermo coolers good or what ......i have a 25 litre one given to me and its new the bloke didnt want it ......ive had it on now for 5 hours its keeping 6 degrees this is what i set it at ...i posted the question on another forum but got very little responce ........is it worth me taking it away for a power site for 5 days in my tent........i can buy a different item if needed ......
Possum3 said
09:23 PM Sep 5, 2022
We have one but it is too large for easy storage - they work well if you like to eat stews and curries, we tend to cook smaller meals so we leave it at home.
Peltier devices are brilliant. You can even stack them for reducing temperatures even further.
But they are shockingly inefficient & completely the wrong device for an esky. More so if camping.
1 hour running a tipical 40 x 40mm 8.0amp 12 volt peltier will only provide 68 watts of cooling.
Get a compressor fridge. My 28L fridge uses about 15AH per 24 hours at 5°C & have the option of down to -22°C if needed.
Whenarewethere said
10:34 PM Sep 5, 2022
You also need a really good heatsink on the Peltier with effective forced cooling.
These are the type of heatsinks I have used on my CPS & will multiple fans. All the Peltier eskys will have pretty underwhelming heatsink & fan setup. Having said that, I replaced the 92mm fan with a 120mm fan in my compressor fridge.
Sorry Tea spoon I read it as Thermo Cookers - the sooner I get back to a proper PC, the better.
Better go to Spec Savers.
TheHeaths said
09:32 AM Sep 6, 2022
tea spoon wrote:
.....question ....are thermo coolers good or what ......i have a 25 litre one given to me and its new the bloke didnt want it ......ive had it on now for 5 hours its keeping 6 degrees this is what i set it at ...i posted the question on another forum but got very little responce ........is it worth me taking it away for a power site for 5 days in my tent........i can buy a different item if needed ......
Thats funny Clifford, as you seem to acknowledge you got the answer over there, and said you would look at buying a better unit. You asked me after I responded whether they performed better on 240 volt. I dont know as I got rid of mine. Ps you have a few more responses there than here.
If you look at model number BD35F page 7 running in an ambient temperature of 32°C the compressor uses 4.0amps 12v at 2000rpm is 231% efficient.
Peltier device
COP(Cooling)=(Cold side Temperature in Kelvin)/(Hot side Temperature-Cold side Temperature) So, Actual efficiency always depends on the temperature difference between hot side and cold side. For example, if a peltier is 5% efficient, its cold side temperature is 0°C(273K) and hot side temperature is 70°C(343K),
Efficiency(Cooling)=5*273/70=19.5%
My 28L fridge needed 1.768kWh over 46 hours or 38.43 watts per hour to cool 10.5 kg of water & also the ambient temperature of 26°C to freeze the water to -22°C. Then the fridge started cycling.
A Peltier is a low voltage device. If you run it off a 240v transformer make sure you add about another 10% inefficiencies.
It is also very important to find the sweet spot of a peltier. But the main issue is that they are simply extremely inefficient. As they cool, heat is the major issue & it needs to be removed at efficiently as possible.
Ambient temperatures for a single layer peltier is an issue. Whereas a compressor fridge will reduce to about 48°C below ambient, as per my fridge test of ambient 26°C & freezing water to -22°C. It probably would have got to -25°C if I left it another day.
It is one thing simply to keep things cold but a fridge needs to have enough capacity to remove heat from putting warm things in the fridge.
Whenarewethere said
11:35 AM Sep 6, 2022
If it's a 5 day trip fill up soft drink bottles 95% lay them on their side in the home freezer for a week. An esky should be at least 50% ice.
We did this before we had a fridge & still had ice after 7 days. Even put some more frozen bottles on top of the esky, they become drinking water as they melt. Cover the whole setup with an old sleeping bag or other insulation you have, bubble wrap will do. But we did build an esky out of foam which had a wall thickness of about 80mm.
Bought ice is a waste of time.
Whenarewethere said
04:58 PM Sep 6, 2022
This will be an interesting experiment.
I bought a 68W/8.5amp 40 x 40mm peltier. I have some Noctua heat pipe CPU heatsinks for 130 watt CPUs. They are large heatsinks with 120mm fan. Some I have 2 fans, push pull setup. They would be a lot larger than in any peltier esky.
So I thought I could use my 28L fridge & place on top a thick extruded styrene foam lid, I have offcuts. Using the same fridge carcass with all the same additional insulation will give a reasonably good comparison of compressor vs peltier.
It will take a bit of setting up & measuring, so you will need to be a bit patient.
Quite frankly I am not expecting much.
Radar said
07:19 AM Sep 7, 2022
tea spoon wrote:
.....question ....are thermo coolers good or what ......i have a 25 litre one given to me and its new the bloke didnt want it ......ive had it on now for 5 hours its keeping 6 degrees this is what i set it at ...i posted the question on another forum but got very little responce ........is it worth me taking it away for a power site for 5 days in my tent........i can buy a different item if needed ......
Hi tea spoon.
When I was working, now retired for 9 years, I used one in the truck as my cooler, I actually brought 2 in about 14 years, I broke the lid on the first one and as far I know the fellow I gave it to still has it. The last one I gave it away to another friend who using it when it for his picnic cooler in his travels.
Funny as I sometimes think I should of kept that one instead of backing my back lifting the compressor frig in and out the ute as they are very light.
There frig performance as such is not great but is better then hot water, never use one to keep food warm but did bump the switch to warm cycle once and was surprised how it heated up.
They do draw consistent 12 volt power (I can not remember the amperage, maybe 5 amps). Would make battery a bit sick after a few hours
We found it great when travelling with our camper trailer, storage of lettus, eggs, butter and we would turn it off when parked up
Whenarewethere said
07:24 PM Sep 7, 2022
I have lapped the back of a piece of 6mm tread plate, 150 x 285mm, an offcut I had. Clamped the peltier down with a Noctua CPU heatsink. The heatsink got hot very quickly without fans, with the two 120mm fans it is barely warm. Even the where the heat pipes come out of the base, they are only warm so the heatsink is working well.
Peltier 7.5amps, Fans 0.2amps at 13.2 volts. I have a 10amp charger on the battery which was on the bulk part of the charging cycle at the time.
I will set it up with thermometers & the rest of the circus over my 28L fridge.
Whenarewethere said
12:05 PM Sep 8, 2022
Some brief notes so far.
Empty fridge with thermometer sitting on the bottom of the fridge. 20°C ambient. Fan exhaust 3°C higher. 7.8 amps including fans clamp meter, 14.18 volts as charger is connected to battery (this would be indicative of running the fridge while driving if you have done your wiring properly & or using a DC-DC charger), it is supplying 7.9 amps.
Bottom of fridge:
1 hour 6.6°C
1.5 hours 4.1°C
2 hours 2.4°C (evaporator -7.3°C)
2.5 hours 1.9°C
3.0 hours 4.7°C (evaporator -8.2°C)
The fridge lid is actually hollow, probably to save 2 cents in manufacturing costs. One day I intend to fill it with insulation, just haven't got around to it. So the 30mm extruded styrene foam will be providing as good if not better insulation from above.
The evaporator plate is -7.3°C at roughly an average distance from the peltier to the edge of the edge, width length average.
One would need to calculate the optimal size evaporator plate for the temperature which one would need to achieve in the fridge. You can get an extremely cold temperature, but the surface area is so small that you don't have any "volume" to cools reasonable mass.
I think this size plate is a reasonable area for the task, probably leaning more to guessing, but the condenser heatsink should have at least 2.5 times the rate of that of the evaporator heatsink.
The condenser heatsink has 0.52m² & the evaporator heatsink (exposed side) has a surface area of 0.048m² including edges. So roughly 10.8333... times the surface area of the evaporator heatsink. Factoring the 3°C exhaust fan increase in temperature, I think that to squeeze out any more efficiency will provide a single digit percentage gain.
An hour later the evaporator plate is simply frosting up which actually creates insulation (snow on roofs of houses is a great insulator as it is mostly air).
Initial thoughts in relation to to the compressor fridge. The evaporator tlhas a surface area of 0.3m², although I haven't measured it directly, it must be somewhat below -25°C.
The peltier evaporator is only 1/6 of the surface area, yet can only reach a temperature of -8°C & at about double the the amps of the compressor fridge.
Both evaporators do frost up, but because the compressor fridge has 6 times the surface area & is a lot colder, there is what I call much more depth to the capacity of a compressor fridge.
I will run the 10.5kg of freezing to compare each setup. Ambient temperature will be a bit in favour of the peltier.
WAWT, I'm glad Tea Spoon didn't ask how the toilet works.........TMI
Cheers Bob
Whenarewethere said
02:46 PM Sep 8, 2022
Bobdown wrote:
WAWT, I'm glad Tea Spoon didn't ask how the toilet works.........TMI
Cheers Bob
Well, we have one which is an P trap & another which is an S trap and as a result .....
Bobdown said
02:55 PM Sep 8, 2022
Whenarewethere wrote:
Bobdown wrote:
WAWT, I'm glad Tea Spoon didn't ask how the toilet works.........TMI
Cheers Bob
Well, we have one which is an P trap & another which is an S trap and as a result .....
Touche !!
Ivan 01 said
03:04 PM Sep 8, 2022
Even after all that, it is common knowledge that those pelteir type coolers are pretty much useless unless they are being used in Victorias south east in the winter.
A bloke told me once that when he was on night shift in Melbourne it kept his soft drink drinkable during the graveyard shift.
My thoughts are that if you need a fridge then buy one.
Whenarewethere said
06:40 AM Sep 9, 2022
At 18 hours & the room at 26°C & centre of thermal mass is 11.7°C, yes, I decided to run heaters to benchmark as close as possible at astronomical cost of current electrical costs to compare the compressor fridge test as best as possible to the peltier. More information to follow.
Clarky 1 said
10:00 AM Sep 9, 2022
The absolute need by some on here to be better than anyone else is sickening.
Do they get a star stamped on the back of their hand after dribbling crap on this forum?
The nonsense and at times, off topic antics, might be the reason that myself and some others just dont bother any more.
DeBe said
11:21 PM Sep 9, 2022
Well i found Whenarewethere's experiment verry enlightening & not dribling crap. Good on him exploring the ineficiencys of peltier devices. Mutch more interesting than some other crap thats been on here lately. Due to the attitude of some on here i dont think Tea spoon will be back any time soon
Whenarewethere said
12:13 AM Sep 10, 2022
tea spoon wrote:
Are thermo coolers good or what I have a 25 litre one
Answer to OP: Yes, with qualifications.
DeBe wrote:
Well i found Whenarewethere's experiment verry enlightening & not dribling crap. Good on him exploring the ineficiencys of peltier devices. Mutch more interesting than some other crap thats been on here lately. Due to the attitude of some on here i dont think Tea spoon will be back any time soon
I installed a 3.8amp peltier fridge in my car in 1980 which also had cooling from the air conditioning, if only I did a bit more grade 3 maths at the time I would have had an even better fridge.
A few more days & I will post my grade 3 table so you can see the difference between a compressor fridge & a peltier fridge.
I couldn't find any efficiency data comparing these two products on the internet & people simply saying get a compressor fridge without qualification one simply ignores these comments.
Since I have a 28L fridge, at the upper end of a peltier sized fridge, & all the other bits off computers I am quite happy to contribute some constructive grade 3 observations.
In the meantime, if you just want a cooler & probably up to 10 litres & are driving a lot then a peltier would be ok if you pre cool the contents.
Anything more than that then get a compressor fridge. It is stating the bleeding obvious but hopefully with some really basic numbers one can be a bit more informed.
It's been an enjoyable & interesting little project. Even the neighbours kid was interested, so that alone was worth it.
Radar said
06:24 AM Sep 10, 2022
Whenarewethere wrote:
tea spoon wrote:
Are thermo coolers good or what I have a 25 litre one
Answer to OP: Yes, with qualifications
DeBe wrote:
Well i found Whenarewethere's experiment verry enlightening & not dribling crap. Good on him exploring the ineficiencys of peltier devices. Mutch more interesting than some other crap thats been on here lately. Due to the attitude of some on here i dont think Tea spoon will be back any time soon
I installed a 3.8amp peltier fridge in my car in 1980 which also had cooling from the air conditioning, if only I did a bit more grade 3 maths at the time I would have had an even better fridge.
A few more days & I will post my grade 3 table so you can see the difference between a compressor fridge & a peltier fridge.
I couldn't find any efficiency data comparing these two products on the internet & people simply saying get a compressor fridge without qualification one simply ignores these comments.
Since I have a 28L fridge, at the upper end of a peltier sized fridge, & all the other bits off computers I am quite happy to contribute some constructive grade 3 observations.
In the meantime, if you just want a cooler & probably up to 10 litres & are driving a lot then a peltier would be ok if you pre cool the contents.
Anything more than that then get a compressor fridge. It is stating the bleeding obvious but hopefully with some really basic numbers one can be a bit more informed.
It's been an enjoyable & interesting little project. Even the neighbours kid was interested, so that alone was worth it.
After all wealth of knowledge on the subject and valuation, my 14 years of using a 24 litre cooler was justified.
It is far better then using ice bricks or having no cooler.
Nice work.
Whenarewethere said
07:43 AM Sep 10, 2022
Radar wrote:
After all wealth of knowledge on the subject and valuation, my 14 years of using a 24 litre cooler was justified. It is far better then using ice bricks or having no cooler.
I agree.
We used ice before our fridge in our last two cars & at the time it worked very well for the type of traveling we did, but we froze our own very large block of ice. I did have a peltier fridge I installed in the car 1980. It worked well but it would have been a lot better based on what I know now.
Data collection tools including a mercury thermometer (one Engel monitor I damaged the external sensor, my own stupidity). Having a number of devices I can calculate an average.
Whenarewethere said
09:21 AM Sep 10, 2022
I can't find my overall notes on the compressor fridge, but it used half the energy & cooled a lot quicker.
This is a torture test freezing 10.5kg of water, so not a realistic real life situation, but it is to show the limits of compressor vs peltier as best as one can reasonably do.
At 42 hours I stuck a Noctua fan with resistor (outside) for a low speed fan inside the fridge to gently move air. It is adding 0.5 watt of heat but I feel at this stage there is an advantage of having an efficient fan in the fridge for cooling.
The evaporator plate is not as cold due to the fan but the 1O.5kg of water seems to be getting cooler quicker.
I will go a bit longer to either freeze the water or to the point where the diminishing returns are not worthwhile.
Whenarewethere said
08:27 PM Sep 11, 2022
I have decided to stop at 3 days because the fridge is not getting any colder than 3.5°C. This has consumed 7kWh (not including heating he room), about 4 times the energy of the compressor to reach -22°C & quicker.
The compressor fridge gets the centre of the ice to -2°C in a day. So you are looking at about 8% or less of the energy consumption with a compressor fridge. Mine only uses typically 3.8 amps when the compressor is running. The peltier uses twice that continuously.
As a small fridge & precooling contents & if you have enough battery resources or 240v these fridges are ok. Also very light weight. But if you need something beyond these limitations get a compressor fridge.
My compressor fridge uses 15AH per 24 hours for 5°C setting.
I noticed how hot & how quickly the heatsink got without fans, within a minute, & then it is completely useless. It's creating about 100 watts of heat plus the heat it is moving to the outside of about 50 watts, so that is about 150 watts of heat. It has to be removed. If your fridge is exhausting warm air the heatsink & or fan is not good enough. At least stick another fan on the outside to move more air through the heatsink.
The exhaust air on this setup was only 3°C above ambient. So if your fridge has a small heatsink & or small fan you will have a much higher temperature above ambient so the fridge will not get as cold. You need to get the exhaust air as close to ambient as possible to get the evaporator side as cold as possible.
120mm fan I stuck inside the fridge for part of the experiment. It did reduce the amount of ice forming on the evaporator plate. It is one of the Noctua fans which are very efficient (I bought these a decade ago) 1.08 watts & put the resistor outside the fridge, it comes with a couple of resistors to reduce fan speed.
If you want to knock up something out of a foam box, or extruded styrene foam (much easier to handle, cut with hand saw or knife & sand) there is nothing difficult. An aluminium cooking tray for the evaporator will do, plus thermal paste, but you would need a sold block (get an offcut from an aluminium fabricator) to clamp the peltier firmly. Fans one could salvage, but get a heatsink with at least 0.5 metres surface area & stick fans on it.
StewG said
05:49 PM Sep 12, 2022
I have a Peltier Effect Cooler/Heater of about 10 litres capacity. It draws about 5amps (at 12VDC) continuously and cannot keep a constant temperature. I stopped trying to use it and bought a real fridge 4 x the size and uses half the power and keeps a constant 4 degrees Celsius. In other words, I wouldn't buy or use one ever again based on that experience. Give me a heat pump or compressor fridge any day.
bobsa said
01:56 PM Sep 14, 2022
No they are not much good , they don't hold temperature ,that is why they make compressor fridges
this only from a Refrigeration Mechanics point of view
Bob
Clarky 1 said
06:02 PM Sep 14, 2022
Numerous posts of crap and a few where the authors spoke the truth.
But hang on WAWT here is your rubber stamp. You get an early mark.
No they are not much good , they don't hold temperature ,that is why they make compressor fridges this only from a Refrigeration Mechanics point of view Bob
Hold on a moment.
Would you lift a 26kgs 12 volt compressor frig from a prime mover everynight because it may not be there in the morning. Abig no.
My lightweight cooler was billiant, my oversized lunch box but the last 4 years it just sat there between the seats of the prime and the night shift never shifted it but had it been an expensive compressor frig it would of been used in someone else's forby.
.....question ....are thermo coolers good or what ......i have a 25 litre one given to me and its new the bloke didnt want it ......ive had it on now for 5 hours its keeping 6 degrees this is what i set it at ...i posted the question on another forum but got very little responce ........is it worth me taking it away for a power site for 5 days in my tent........i can buy a different item if needed ......
www.supercheapauto.com.au/p/ridge-ryder-ridge-ryder-thermo-cooler-warmer-12-litre/577075.html
Peltier devices are brilliant. You can even stack them for reducing temperatures even further.
But they are shockingly inefficient & completely the wrong device for an esky. More so if camping.
1 hour running a tipical 40 x 40mm 8.0amp 12 volt peltier will only provide 68 watts of cooling.
Get a compressor fridge. My 28L fridge uses about 15AH per 24 hours at 5°C & have the option of down to -22°C if needed.
You also need a really good heatsink on the Peltier with effective forced cooling.
These are the type of heatsinks I have used on my CPS & will multiple fans. All the Peltier eskys will have pretty underwhelming heatsink & fan setup. Having said that, I replaced the 92mm fan with a 120mm fan in my compressor fridge.
https://noctua.at/en/nh-u14s-dx-4189/specification
Better go to Spec Savers.
Thats funny Clifford, as you seem to acknowledge you got the answer over there, and said you would look at buying a better unit. You asked me after I responded whether they performed better on 240 volt. I dont know as I got rid of mine. Ps you have a few more responses there than here.
Danfoss compressor data pdf 1.1MB file
https://www.mmair.com/wp-content/uploads/2016/09/BD35.BD50.Danfoss.pdf
If you look at model number BD35F page 7 running in an ambient temperature of 32°C the compressor uses 4.0amps 12v at 2000rpm is 231% efficient.
Peltier device
COP(Cooling)=(Cold side Temperature in Kelvin)/(Hot side Temperature-Cold side Temperature) So, Actual efficiency always depends on the temperature difference between hot side and cold side. For example, if a peltier is 5% efficient, its cold side temperature is 0°C(273K) and hot side temperature is 70°C(343K),
Efficiency(Cooling)=5*273/70=19.5%
My 28L fridge needed 1.768kWh over 46 hours or 38.43 watts per hour to cool 10.5 kg of water & also the ambient temperature of 26°C to freeze the water to -22°C. Then the fridge started cycling.
https://thegreynomads.activeboard.com/t65059593/extra-fridge-insulation-wattage-test/
A Peltier is a low voltage device. If you run it off a 240v transformer make sure you add about another 10% inefficiencies.
It is also very important to find the sweet spot of a peltier. But the main issue is that they are simply extremely inefficient. As they cool, heat is the major issue & it needs to be removed at efficiently as possible.
Ambient temperatures for a single layer peltier is an issue. Whereas a compressor fridge will reduce to about 48°C below ambient, as per my fridge test of ambient 26°C & freezing water to -22°C. It probably would have got to -25°C if I left it another day.
It is one thing simply to keep things cold but a fridge needs to have enough capacity to remove heat from putting warm things in the fridge.
If it's a 5 day trip fill up soft drink bottles 95% lay them on their side in the home freezer for a week. An esky should be at least 50% ice.
We did this before we had a fridge & still had ice after 7 days. Even put some more frozen bottles on top of the esky, they become drinking water as they melt. Cover the whole setup with an old sleeping bag or other insulation you have, bubble wrap will do. But we did build an esky out of foam which had a wall thickness of about 80mm.
Bought ice is a waste of time.
This will be an interesting experiment.
I bought a 68W/8.5amp 40 x 40mm peltier. I have some Noctua heat pipe CPU heatsinks for 130 watt CPUs. They are large heatsinks with 120mm fan. Some I have 2 fans, push pull setup. They would be a lot larger than in any peltier esky.
So I thought I could use my 28L fridge & place on top a thick extruded styrene foam lid, I have offcuts. Using the same fridge carcass with all the same additional insulation will give a reasonably good comparison of compressor vs peltier.
It will take a bit of setting up & measuring, so you will need to be a bit patient.
Quite frankly I am not expecting much.
Hi tea spoon.
When I was working, now retired for 9 years, I used one in the truck as my cooler, I actually brought 2 in about 14 years, I broke the lid on the first one and as far I know the fellow I gave it to still has it. The last one I gave it away to another friend who using it when it for his picnic cooler in his travels.
Funny as I sometimes think I should of kept that one instead of backing my back lifting the compressor frig in and out the ute as they are very light.
There frig performance as such is not great but is better then hot water, never use one to keep food warm but did bump the switch to warm cycle once and was surprised how it heated up.
They do draw consistent 12 volt power (I can not remember the amperage, maybe 5 amps). Would make battery a bit sick after a few hours
We found it great when travelling with our camper trailer, storage of lettus, eggs, butter and we would turn it off when parked up
I have lapped the back of a piece of 6mm tread plate, 150 x 285mm, an offcut I had. Clamped the peltier down with a Noctua CPU heatsink. The heatsink got hot very quickly without fans, with the two 120mm fans it is barely warm. Even the where the heat pipes come out of the base, they are only warm so the heatsink is working well.
Peltier 7.5amps, Fans 0.2amps at 13.2 volts. I have a 10amp charger on the battery which was on the bulk part of the charging cycle at the time.
I will set it up with thermometers & the rest of the circus over my 28L fridge.
Some brief notes so far.
Empty fridge with thermometer sitting on the bottom of the fridge. 20°C ambient. Fan exhaust 3°C higher. 7.8 amps including fans clamp meter, 14.18 volts as charger is connected to battery (this would be indicative of running the fridge while driving if you have done your wiring properly & or using a DC-DC charger), it is supplying 7.9 amps.
Bottom of fridge:
1 hour 6.6°C
1.5 hours 4.1°C
2 hours 2.4°C (evaporator -7.3°C)
2.5 hours 1.9°C
3.0 hours 4.7°C (evaporator -8.2°C)
The fridge lid is actually hollow, probably to save 2 cents in manufacturing costs. One day I intend to fill it with insulation, just haven't got around to it. So the 30mm extruded styrene foam will be providing as good if not better insulation from above.
The evaporator plate is -7.3°C at roughly an average distance from the peltier to the edge of the edge, width length average.
One would need to calculate the optimal size evaporator plate for the temperature which one would need to achieve in the fridge. You can get an extremely cold temperature, but the surface area is so small that you don't have any "volume" to cools reasonable mass.
I think this size plate is a reasonable area for the task, probably leaning more to guessing, but the condenser heatsink should have at least 2.5 times the rate of that of the evaporator heatsink.
The condenser heatsink has 0.52m² & the evaporator heatsink (exposed side) has a surface area of 0.048m² including edges. So roughly 10.8333... times the surface area of the evaporator heatsink. Factoring the 3°C exhaust fan increase in temperature, I think that to squeeze out any more efficiency will provide a single digit percentage gain.
An hour later the evaporator plate is simply frosting up which actually creates insulation (snow on roofs of houses is a great insulator as it is mostly air).
Initial thoughts in relation to to the compressor fridge. The evaporator tlhas a surface area of 0.3m², although I haven't measured it directly, it must be somewhat below -25°C.
The peltier evaporator is only 1/6 of the surface area, yet can only reach a temperature of -8°C & at about double the the amps of the compressor fridge.
Both evaporators do frost up, but because the compressor fridge has 6 times the surface area & is a lot colder, there is what I call much more depth to the capacity of a compressor fridge.
I will run the 10.5kg of freezing to compare each setup. Ambient temperature will be a bit in favour of the peltier.
WAWT, I'm glad Tea Spoon didn't ask how the toilet works.........TMI
Cheers Bob
Well, we have one which is an P trap & another which is an S trap and as a result .....
Touche !!
A bloke told me once that when he was on night shift in Melbourne it kept his soft drink drinkable during the graveyard shift.
My thoughts are that if you need a fridge then buy one.
At 18 hours & the room at 26°C & centre of thermal mass is 11.7°C, yes, I decided to run heaters to benchmark as close as possible at astronomical cost of current electrical costs to compare the compressor fridge test as best as possible to the peltier. More information to follow.
Do they get a star stamped on the back of their hand after dribbling crap on this forum?
The nonsense and at times, off topic antics, might be the reason that myself and some others just dont bother any more.
Answer to OP: Yes, with qualifications.
I installed a 3.8amp peltier fridge in my car in 1980 which also had cooling from the air conditioning, if only I did a bit more grade 3 maths at the time I would have had an even better fridge.
A few more days & I will post my grade 3 table so you can see the difference between a compressor fridge & a peltier fridge.
I couldn't find any efficiency data comparing these two products on the internet & people simply saying get a compressor fridge without qualification one simply ignores these comments.
Since I have a 28L fridge, at the upper end of a peltier sized fridge, & all the other bits off computers I am quite happy to contribute some constructive grade 3 observations.
In the meantime, if you just want a cooler & probably up to 10 litres & are driving a lot then a peltier would be ok if you pre cool the contents.
Anything more than that then get a compressor fridge. It is stating the bleeding obvious but hopefully with some really basic numbers one can be a bit more informed.
It's been an enjoyable & interesting little project. Even the neighbours kid was interested, so that alone was worth it.
Well i found Whenarewethere's experiment verry enlightening & not dribling crap. Good on him exploring the ineficiencys of peltier devices. Mutch more interesting than some other crap thats been on here lately. Due to the attitude of some on here i dont think Tea spoon will be back any time soon
After all wealth of knowledge on the subject and valuation, my 14 years of using a 24 litre cooler was justified.
It is far better then using ice bricks or having no cooler.
Nice work.
I agree.
We used ice before our fridge in our last two cars & at the time it worked very well for the type of traveling we did, but we froze our own very large block of ice. I did have a peltier fridge I installed in the car 1980. It worked well but it would have been a lot better based on what I know now.
Data collection tools including a mercury thermometer (one Engel monitor I damaged the external sensor, my own stupidity). Having a number of devices I can calculate an average.
I can't find my overall notes on the compressor fridge, but it used half the energy & cooled a lot quicker.
This is a torture test freezing 10.5kg of water, so not a realistic real life situation, but it is to show the limits of compressor vs peltier as best as one can reasonably do.
At 42 hours I stuck a Noctua fan with resistor (outside) for a low speed fan inside the fridge to gently move air. It is adding 0.5 watt of heat but I feel at this stage there is an advantage of having an efficient fan in the fridge for cooling.
The evaporator plate is not as cold due to the fan but the 1O.5kg of water seems to be getting cooler quicker.
I will go a bit longer to either freeze the water or to the point where the diminishing returns are not worthwhile.
I have decided to stop at 3 days because the fridge is not getting any colder than 3.5°C. This has consumed 7kWh (not including heating he room), about 4 times the energy of the compressor to reach -22°C & quicker.
The compressor fridge gets the centre of the ice to -2°C in a day. So you are looking at about 8% or less of the energy consumption with a compressor fridge. Mine only uses typically 3.8 amps when the compressor is running. The peltier uses twice that continuously.
As a small fridge & precooling contents & if you have enough battery resources or 240v these fridges are ok. Also very light weight. But if you need something beyond these limitations get a compressor fridge.
My compressor fridge uses 15AH per 24 hours for 5°C setting.
I noticed how hot & how quickly the heatsink got without fans, within a minute, & then it is completely useless. It's creating about 100 watts of heat plus the heat it is moving to the outside of about 50 watts, so that is about 150 watts of heat. It has to be removed. If your fridge is exhausting warm air the heatsink & or fan is not good enough. At least stick another fan on the outside to move more air through the heatsink.
The exhaust air on this setup was only 3°C above ambient. So if your fridge has a small heatsink & or small fan you will have a much higher temperature above ambient so the fridge will not get as cold. You need to get the exhaust air as close to ambient as possible to get the evaporator side as cold as possible.
120mm fan I stuck inside the fridge for part of the experiment. It did reduce the amount of ice forming on the evaporator plate. It is one of the Noctua fans which are very efficient (I bought these a decade ago) 1.08 watts & put the resistor outside the fridge, it comes with a couple of resistors to reduce fan speed.
If you want to knock up something out of a foam box, or extruded styrene foam (much easier to handle, cut with hand saw or knife & sand) there is nothing difficult. An aluminium cooking tray for the evaporator will do, plus thermal paste, but you would need a sold block (get an offcut from an aluminium fabricator) to clamp the peltier firmly. Fans one could salvage, but get a heatsink with at least 0.5 metres surface area & stick fans on it.
this only from a Refrigeration Mechanics point of view
Bob
Numerous posts of crap and a few where the authors spoke the truth.
But hang on WAWT here is your rubber stamp. You get an early mark.
Hold on a moment.
Would you lift a 26kgs 12 volt compressor frig from a prime mover everynight because it may not be there in the morning. Abig no.
My lightweight cooler was billiant, my oversized lunch box but the last 4 years it just sat there between the seats of the prime and the night shift never shifted it but had it been an expensive compressor frig it would of been used in someone else's forby.
As the old saying goes, "horses for courses".