EcoRenovator  

Go Back   EcoRenovator > Improvements > Geothermal & Heat Pumps
Advanced Search
 


Blog 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 09-21-15, 12:58 PM   #1
marx290
Vapor Compression Goon
 
marx290's Avatar
 
Join Date: Mar 2013
Location: Portland, OR
Posts: 63
Thanks: 11
Thanked 22 Times in 11 Posts
Send a message via Yahoo to marx290
Talking Mini Brushless DC Compressor

A friend of mine recently acquired a small brushless DC compressor for me to work with. He would like to develop some mobile cooling devices for a teardrop trailer he is planning. I was going to build a small air to air cooling system, but with the temperature dropping lately, and the relative humidity rising, I'm going after a dehumidifier for now.

Look at the pics; isn't it cute!?

It's a rotary compressor, 2.7cc, 1700-2900 RPM, 50mL oil, 12VDC

Other models are available which have a high speed of 6000 RPM, and other voltages as well.

eBay listing for 12VDC Refrigeration Compressor - Brushless DC

I've had an interesting time checking and changing the oil in the compressor. Displacing/burping the air is the biggest issue. I utilize a large syringe and needle, along with a very thin tube attached to the needle, for the job. Oil migration is an issue, I'm sure.

I'm running a capillary tube system right now. It is too long, so I'll be shortening that today.

Somebody else should buy one of these, and build something!










Attached Thumbnails
Click image for larger version

Name:	20150915_175327.jpg
Views:	4978
Size:	509.2 KB
ID:	5901   Click image for larger version

Name:	20150915_180811.jpg
Views:	4512
Size:	510.0 KB
ID:	5902   Click image for larger version

Name:	20150918_201807.jpg
Views:	3864
Size:	505.1 KB
ID:	5903  
__________________

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Last edited by Daox; 09-24-15 at 07:57 AM..
marx290 is offline   Reply With Quote
The Following 2 Users Say Thank You to marx290 For This Useful Post:
AC_Hacker (09-22-15), jeff5may (09-26-15)
Old 09-22-15, 11:58 AM   #2
AC_Hacker
Supreme EcoRenovator
 
AC_Hacker's Avatar
 
Join Date: Mar 2009
Location: Portland, OR
Posts: 4,004
Thanks: 303
Thanked 723 Times in 534 Posts
Default

Way cool work!

How are you varying the speed of the compressor??

-AC
__________________
I'm not an HVAC technician. In fact, I'm barely even a hacker...
AC_Hacker is offline   Reply With Quote
Old 09-22-15, 03:24 PM   #3
marx290
Vapor Compression Goon
 
marx290's Avatar
 
Join Date: Mar 2013
Location: Portland, OR
Posts: 63
Thanks: 11
Thanked 22 Times in 11 Posts
Send a message via Yahoo to marx290
Default

Thanks, AC_Hacker! I'm not doing much in the way of varying the speed; running with all the power this little baby will take! There is a small potentiometer on the control board that allows me to vary the speed, with the aid of a small screwdriver.

I'm powering it with a deep cycle battery for now, but my buddy has a small regulated power supply to run it.

I've shortened the capillary tubing several times now. Down to 8 feet of 0.031 now. I'm getting fairly close to the right length, however I might have an issue with pressure drop across the evaporator. I will be adding another port on that side of the evaporator to look for the drop.

Oil migration is definitely an issue, I'm finding.
__________________

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
marx290 is offline   Reply With Quote
Old 09-23-15, 10:39 PM   #4
AC_Hacker
Supreme EcoRenovator
 
AC_Hacker's Avatar
 
Join Date: Mar 2009
Location: Portland, OR
Posts: 4,004
Thanks: 303
Thanked 723 Times in 534 Posts
Default

Quote:
Originally Posted by marx290 View Post
There is a small potentiometer on the control board that allows me to vary the speed, with the aid of a small screwdriver.
That's pretty cool that you can change speed by analog means (Your pot could be replaced by an analog circuit to control speed). According to the fine print, you can change the speed through digital means as well.


Quote:
Originally Posted by marx290 View Post
Oil migration is definitely an issue, I'm finding.
How are you detecting oil migration??

-AC
__________________
I'm not an HVAC technician. In fact, I'm barely even a hacker...
AC_Hacker is offline   Reply With Quote
Old 09-24-15, 10:54 AM   #5
TechShop
FNG
 
Join Date: Jul 2015
Location: Washington
Posts: 71
Thanks: 8
Thanked 19 Times in 13 Posts
Default

That sure is a neat little unit.

It looks like the board that comes with it can run a complete system including the fans.
That must have an original application in RV refrigerators, portable coolers, etc.
TechShop is offline   Reply With Quote
Old 09-24-15, 05:17 PM   #6
AC_Hacker
Supreme EcoRenovator
 
AC_Hacker's Avatar
 
Join Date: Mar 2009
Location: Portland, OR
Posts: 4,004
Thanks: 303
Thanked 723 Times in 534 Posts
Default

Quote:
Originally Posted by TechShop View Post
That sure is a neat little unit.

It looks like the board that comes with it can run a complete system including the fans.
That must have an original application in RV refrigerators, portable coolers, etc.
I have an ice-cream machine that has a different, but tiny compressor. Very useful.

-AC
__________________
I'm not an HVAC technician. In fact, I'm barely even a hacker...
AC_Hacker is offline   Reply With Quote
Old 09-24-15, 08:02 PM   #7
marx290
Vapor Compression Goon
 
marx290's Avatar
 
Join Date: Mar 2013
Location: Portland, OR
Posts: 63
Thanks: 11
Thanked 22 Times in 11 Posts
Send a message via Yahoo to marx290
Default

AC_Hacker, I will probably look into a better speed control. Perhaps, once I build refrigerator, or something like that, I will be more interested in variable speed. I am mainly interested in the small size, and at 80 watt input power, I don't need to turn it down anymore! An electronically controlled feedback loop that set the speed to match the load might be fascinating, but beyond my level of interest at this time. Another idea for the variable speed, is to give the operator of say, a refrigerator, some information about the power consumption of the unit, along with the run times and duty cycles; they could then turn up or down the the compressor speed, depending on their desires to gain efficiency or for faster cool down. Most people probably wouldn't care, but I think it would be neat.

Quote:
Originally Posted by TechShop View Post
That sure is a neat little unit.

It looks like the board that comes with it can run a complete system including the fans.
That must have an original application in RV refrigerators, portable coolers, etc.
Yes, the board will run a condenser fan, evaporator fan, accept some digital signals for run speed, has a temp sensor for compressor overheat, has a shunt for overcurrent protection, and of course has the little pot for manually adjusting speed.

I don't know of too many appliances that are using these compressors specifically. I've seen some pics of appliances that include refrigerators, freezers, dehumidifiers, portable refrigerators, liquid chillers, and more.

The company Purswave makes a very similar compressor to the one I have; so similar that it may be the same manufacturer, I'm not sure. Here's some of the products they make. Some of the compressors are larger, but many are DC.

Refrigeration Appliance -

Compressors this small and smaller, are being utilized a lot in personal cooling for people who must wear environmental protection suits of some sort. The US company Aspen has a military contract to produce tiny 1.9 cc rotary compressors for this purpose.

Quote:
How are you detecting oil migration??

-AC
So, the oil thing is interesting. I don't have much experience changing oil in hermetic compressors; by that I mean none. I wasn't sure how much oil was in the compressor from factory, so I emptied it and charged 50 mL of POE with a syringe and needle. The copper lines I brazed on the compressor were going to make it difficult to check the oil level at a later time, but I figured it out. I utilized flare fittings in my system, since it is experimental, and they allow me to make quick changes, or do things like check the oil charge in the compressor.

The first time I pulled the refrigerant charge out, a good bit of oil came with it, from the suction line. I unhooked the compressor, an flipped it upside down. To force the oil out of the discharge line, I had to force air into the shell with a piece of wire insulation stuck to the needle of the syringe. Measuring the remaining oil, I found I had lost about 10 mL of oil; probably not enough to cause damage, but definitely oil migration. How this might play out in the long run, I don't know.

I have since moved the suction service valve, and I find I do not lose as much oil when recovering refrigerant. Whether or not it is returning to the compressor during operation, is another question. I must look into oil retun methods like traps, and wicks.

That is all for now, time for dinner.

Tomorrow night, I'll be adding some features, and nailing down the proper length of capillary tubing.

-Marx
__________________

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
marx290 is offline   Reply With Quote
Old 09-25-15, 08:13 AM   #8
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,428
Thanks: 431
Thanked 619 Times in 517 Posts
Send a message via Yahoo to jeff5may
Default

Take a look at Jake's latest thread:
http://ecorenovator.org/forum/geothe...o-heating.html

He has been doing research on an oil trap/separator to use in his new concoction. As I write this post, he is gearing up for yet another build of groundbreaking (literally) and unconventional nature. His homework could save you some time and effort rigging up an oil trap.

I wish you both good luck and godspeed.
jeff5may is offline   Reply With Quote
Old 09-26-15, 12:10 PM   #9
marx290
Vapor Compression Goon
 
marx290's Avatar
 
Join Date: Mar 2013
Location: Portland, OR
Posts: 63
Thanks: 11
Thanked 22 Times in 11 Posts
Send a message via Yahoo to marx290
Default

Thanks Jeff. It is an interesting thread. My little compressor is going to need some special attention when it comes to the oil. I will most certainly consider building a better draining system, but I don't want to rely on that. I'll keep my eyes open for more progress.
__________________

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
marx290 is offline   Reply With Quote
Old 01-16-19, 11:43 AM   #10
pavel
Lurking Renovator
 
Join Date: Jan 2019
Location: Czech Rep.
Posts: 14
Thanks: 0
Thanked 4 Times in 3 Posts
Default Interesting

Thanks for posting

pavel is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 01:04 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design