Designing an Advanced Heat Pump Controller
 

This thread is intended for discussions which could result in a fully featured, state of the art heat pump controller.

Advanced hardware, software, full features set.

-AC_Hacker

"Simple" : start by revising your other thread:

VFD for 3 phase compressor

VFD for 3 phase condensor fan

NO reversing valve, HP only

VFD for 3 phase for ground loop circulation (or pump and dump pump, etc) pump

Flow meter

Turbine expansion with PM 6 phase micro generator

Some NTC resistors for indoor/outdoor/various line temperatures

Strain gauges on liquid and suction lines in a couple of places for pressure.

Laptop connections, serial USB

ACCURATE Mollier diagram/table of system components

Take all the inputs, Program laptop (e.g. Labview or similar)to compare to optimum operation point on Mollier diagram, readjust the VFDs for overall maximum COP every few minutes. Load the turbine expansion generator (by feeding 60 Hz back to line thru inverter) to control refrigerant flow consistent with optimum Molllier diagram COP point.

Program appropriate shutdown/safety points.

Similar algorithms for solar array peak power points can be used.

How do you intend to provide the VFD function?

Can you elaborate in this? What is it and why do you want it?

-AC

VFD simply could be commercial drivers, literally hundreds of different models.
1st ebay hit as example:
High Quality 3HP 2 2KW 10A 220 250V Variable Frequency Drive Inverter VFD New A7 | eBay

Nearly all of these provide for RS422 or 1515 interface control.

Turbine expansion with PM 6 phase micro generator
To eliminate throttling losses from txv or expansion valve, the liquid to vapor transformation can be done by a turbine that recovers the lost energy of liquid to vapor transformation. Typically used in near absolute zero refrigeration setups.
Turboexpander - Wikipedia, the free encyclopedia
PM= permanent magnet, 6 phase to give smoother dc link for inverter and increase efficiency.

I have had great success using an ejector to recover the energy that went into raising the pressure. No moving parts apart from the refrigerant itself and it nicely gives you two stages of cooling for better dehumidification.

I checked out your VFD link, pretty good prices.

In your previous post, you recommended using 3-phase for the compressor, fan, and circulating pumps.

I can see that the VFDs as you pointed out would be appropriate for precisely controlling a compressor, but what about the kind of VFDs would you use to drive a fan? The smallest VFD I've come across are about 1HP.

Then there's the issue of VFD for circ pumps. Do 3-phase circ pumps exist in the size that would be selected for a typical home? I would guess that the typical not-so-well-insulated home would require a heating system of something like 3.5 Tons, and the circ pumps could run in the 100 watt range, and sometimes, in a well designed radiant system, even less... like maybe 60 watts... I do think you are on to something, in fact, I think it's the way of the future. But do 3-phase VFDs and fans and pump motors in home sizes exist?

-AC

Hi,

The use of 3phase AC motors is a small step towards higher efficiency.
One problem, if you run a motor with VFD on 100% it is less efficient than the single phase counterpart. This is due the losses of the VFD.
Other issue is, BLDC motors are more effective. :-)
For circulation pump it's easy you can't beat (in price, simplicity and efficiency) the off the shelf units like Grundfos Alpha2
http://net.grundfos.com/Appl/WebCAPS...re-4352964.pdf
You can get 1/2-1/3 electric consumption from it than a single phase ac pump.
Biger problem to get BLDC (non circulation)pump, compressor and fan motor. I don't know if those are available as standard products...

VFDs are available from as small as 100W. I run my well pump from a 400W VFD on 23Hz, for passive cooling purposes.
http://ecorenovator.org/forum/attach...pfirsttest-jpg rightmost device in electrical box.

T.

Thanks, great information!!

Where do you get the small VFD?

-AC

Not the case if you use FOC (field oriented control). FOC essentially finds the most optimum V/Hz ratio to use at a given frequency. It's especially efficient on greatly varying loads like compressors.