Subject: Low power HVAC with vortex tubes

From: [email-masked] (Nick Pine)
Date: 9 Oct 1996 17:10:45 -0400

Meanwhile, in Siberia...

Valerie Kotelnikov ([email-masked]), who works for the Tuvinian Institute of
the Russian Academy of Sciences, and has recently published a paper on vortex
technology, and has several issued patents on renewable energy technology
(ie he seems to know what he's talking about, unlike me :-), has recently
been inventing an air-air heat pump using an electric fan, that (so far)
moves 18 times the electrical input power as heat, while more typical heat
pumps use more expensive and complicated hardware and refrigerant gases
like Freon to move only 3 times as much heat as the input power (COP=3.)

Can we heat a house with some sort of vortex tube, using the basement floor?

Valerie describes one of his tiny low-speed vortex heat pump experiments:

(After my Rushlish translation :-)

The tube was 8 inches tall with a top diameter of 7.2 inches and a bottom
diameter of 10.4 inches and a cone angle of 7 degrees. Cylindrical vortex
tubes typically have length/diameter ratios of 30-50. Conical shaped ones
can be shorter. Jet-engine-types which compress the air significantly can
be still shorter, and if the output propellor despins and slows down the
air, removing its kinetic energy, they can be even more efficient.

[Professional Engineer Norman Saunders told me on February 2, 1996, as
we were driving from Boston to Maine, that he has been wanting to build
one of these for a long time, for a ground-coupled air->liquid heat pump
application. He said this was described in one of his proprietary files,
but he did not ask me to keep this information to myself, and he didn't
seem interested in pursuing another patent. He's 80 years old now, and
he has 12 patents already :-) On the other hand, Valerie asked me to post
the results of his experiment here. Norman said one of the problems in
building this is finding a small jet engine. Jet engines aren't cheap,
or quiet, and they would make far more heat than a house needs.]

The exit area was a 1.2 inch diameter hole.

I used a 2.4 watt electric fan. Yes, 2.4 watts, less than 3 watts.

The airflow was 0.00523 liters/second, about 0.01 cfm. 

I wrote:

>It seems to me that a larger experiment would be useful, Val, with a larger
>airflow and a taller and larger diameter tube, eg a tube 1 m or 2 m tall
>and an input power of 100 watts, and an airflow of 1000 cfm.

Yes, sure, but I have not money enough. It is very hard time here now. I need
to find some money for food for my daughters. We don't get our salary during
three month which must be paid us earlier.

I didn't think to measure the air velocity, it was about 40 meters/second,
I think, ie 90 mph, high for cars but not fast for an air vortex. Typical
vortex tubes have 100,000 rpm in 1-2 inch diameter. About 10,000 m/s. Vortex
tubes made by Vortec, Inc. have 120 C hot air and -40 C cold air outputs.

The input air temperature was from 62F to 82F, and the output air was
about 6-7 degrees C more than the input temperature.

Heat power Q = 1009 J/kg*grad * difference of temp * mass

or for my case  Q = 1009 * 0.0063 * 7 = 44.1 watts

so COP = 44.1/2.4 = 18.

It is high for this unit. I had COP=7 before. The output airflow temp depends
on the rate of flow. For 7, I used a flow rate of less than this 6.3 g/s.

>Let's try this, Val: suppose we want to heat a house with 90 F air with 55 F
>basement air. Raise the temp of the basement air 35 F, heat the house, and
>return 35 F air to the basement to warm up again? Maybe 1 kW. How would we
>do that? What would the flow rate and fan power be? What air velocity and
>static pressure? What diameter and tube length? Would you extract some
>heat from the hotter air through the walls of the tube?
 
>I may extract heat through walls of tube, and I may extract hot air also.

>Sounds good. Even simpler. Can we put more numbers on this picture?

                   90 F air to 70 F house ==>
                     DT = 20 F, about 10 K.   

                           70 F     First floor? Second floor? Third floor?
..........................   |   ................................
               55 F air-> 100 watt <-55 F air
			 |  fan? |
                         |       |
                         |   s   |  -->further heat extracted from tube wall,
  1 m^3/sec of air   |   |   h   |         to further heat rising 90 F air
  with 1 K delta T       |   a   |  D = ?  with compressed input air?
  moves about            |   f   |
  1 kW, right?     40 D? |   t   |  l/s = 1 kW/10 K = 100?
                         |   ?   |                  ~ 200 cfm
                         |       |  
                     |   |       |
                         |       |
                          50 watt               ^
slow moving 90 F air <-- windmill? --> 90 F air |
                             |
                     <--------------->  air returned from house at 35 F
...........................................................................
               30' x 30', 55 F basement floor warms air back up to 55 F

Can we do this so

35 F cold air flows out from the center of the tube at the bottom, and
55 F stratified basement warm air flows into the tube at the top, and
90 F air flows out from the bottom rim of the tube up into the house, and
70 F house air flows from the house floor into the top center of the tube?

With a fan blowing air down from the top through a propellor at the bottom,
connnected by a rotating shaft? Or perhaps the windmill at the bottom should
be attached to an induction motor, and used as an electrical generator.

This newsgroup publication is intended to be a bar to patenting, under
USC 102/103, and a suggestion that this technique be further developed. 

Nick