AKV versus TEV

[Peter_1]

Need some good advice:
Had a meeting yesterday with an engineering office (EO).
They had prescribed AKV's where I had suggested TEV's.

Their argument was that they could lower the energy bill with at least 15%. That sounded music in the ears of the owner but for me it seemed figures Danfoss themselves gave them.

He said that decreasing one 1°C in condensing pressure can lower the energy bill with 2%. Correct you think?

The argument was that they with the AKV's can lower the condensing pressure significantly and rise suction pressure, without loosing a good liquid injection in the evaporator.

I stated that the biggest advantage should be lowering the condensing pressure but that this can also be done with conventional TEV's if you had selected them to this 'special' working conditions (= low condensing pressure)

He said that my condensing pressure should follow the outside temperature (which is of course correct) but that the injection of the AKV's is constantly adapted to the outside temperature.
What he tried to explain - I think - is when the HP decreases due to lower ambient temperatures, the injection pulse should also been longer to remain at the same SH setting.

I argued that if the condensing pressure goes up and down with TEV's, then the sensing element of my TEV will send a signal - in this case a mechanical or pressure signal and not electronic - to my TEV so that a constant superheat will be maintained if Hp decreases whereby TEV injects not enough liquid. Same - perhaps a little bit higher - as with AKV's.

He said that we then needed to go on site (with TEV's) several times a year, each time the outside temperatures should change to adapt the superheat settings of all our TEV's.
I completely disagreed whit that.

If you look in the manuals of Danfoss (haven't them here not with me), then you can see that TEV's still keeps function properly even with low DP's over it. (but with a lower capacity at lower DP's of course)

My point was - but I can be wrong - that the higher price of AKV's, compared to TEV's will never be repaid by a lower energy bill.
We are talking about a small meat factory with 10 evaporators in the range from 2 kW till 7 kW, total capacity 45 kW.

We also proposed a heat reclaim for water (+/- 1.000 l and additional lowering of condensing pressure) but now they doubt that the costs for this will ever be repaid.
We even proposed a ground coil below the inclined loading docks (we did this already twice) to de-ice them and make so also an additional condenser.

That should have lowered the energy bill.

So, I need some feedback from you guys.
Where am I wrong, where am I right, what different opinions you have, what arguments can be given to justify my idea's? Numbers, tests, testimonials, calculations... anything is welcome because we want this case.

Just found this pdf http://mfnl.xjtu.edu.cn/edu-dk-et/St...ion_system.pdf

I doubt if this is a 100% neutral test. It's done in Denmark with Danfoss material, Danish professors,measured with Danfoss material...