High Temp Heat Pumps

[nike123]

Refrigerants which would thermodinamically work at those temperature are made up of heavy molecules. The two most promising, from a rapid research, are RC318 (AKA octafluorocyclobutane, C4F8) or R718 (AKA water).

Water and compressor are not for love making!

[US Iceman]

I took a quick look at iso-butane. The pressure ratio would be about 2.4:1 and a differential pressure of 230 psi (~15 bar).

So it would need a steel case and some other special requirements.

I still think this is in the realm of possible... But it's going to take more time than 15-20 minutes to development a solid plan.

[SteinarN]

How is it going with your high temp heat pump US Iceman?

[US Iceman]

Hi SteinarN.

I have not started on it yet.

I have been waiting for some information from the client. Not sure why they are taking so long, but will be investigating the reasons for the delay.

[SteinarN]

What capasity is it supposed to have?

[US Iceman]

Somwhere around 0.9 MW cooling, therefore the heating will be slightly higher.

[rsandor]

I`m new here and also interested in high temp output heat pumps.
My house is already heated by panel radiators running from a gas fired boiler. Already changed windows/doors, improved outer insulation of walls. It would be great investment to make floor/wall heating, hardly to add more radiators. The total capacity of radiators are near calculated heat load of house (around 16kW on 80m2), so on cold days (we have about 7 days with -20C yearly) 80C of forward water (don`t know the return temp and flowrate) is required to maintain 22C in house. I heard that some improvements are made in heat pump technology, and it is now possible to achive higher water temperatures with reasonable COP/EER. Maybe with carbon-dioxide based HP? Advice me would it be economical to invest in vertical closed loop GSHP with the existing heating system?

[aeb200]

Heat pumps for domestic use are very en-vogue at the mo everyone is talking about ground source/ domestic hot water etc.

Sadly gas/oil boilers are always going to be much cheaper to buy because there are less components and public demand is far greater.

only when gas /oil are no longer widely available will electrcity (by nuclear or coal power stns) become comparatively cheap. Until this time heat pumps aren't economically viable. For the home at least.

In Japan electricity is cheaper than gas or oil so domestic hp are widely available. For the last 10 yrs they have developed a co2 heat pump which can heat water efficiently see below link.


http://en.wikipedia.org/wiki/EcoCute

The japs are far ahead of the race

[rsandor]

Thx aeb200! Following Your link I found very useful site ...r744... and disappointingly for me the next answer regarding space heating by Dr. S. Girotto:
"...It must be stressed that many people, listening about the features of this product, are attracted by high temperatures of water (i.e. 80°C) at the end
of process and erroneously believe that it is possible to use a CO2 heat pump to supply hot water to a space heating system operating, as an example, with
radiators, with return temperature relatively high, i.e. 55-60°C.
This is not possible, as a CO2 heat pump is not suited for high temperature space heating system, due to high return temperature required by these solutions.
High return temperature means higher temperature of CO2 at the end of heat rejection process (i.e with return water at 50°C CO2 temperature at gas cooler
out would be approximately 55°C) and consequently very poor efficiency and capacity..."
Is that the final word for my problem? No reasonable way of converting heat form range 10-80C to range 80-55C?

[NoNickName]

That is not true. The efficiency drop as the return water increases, but this has nothing to do with the feasibility or not.

[ian g]

Has anyone had a look at the mitsi high temp unit that gos on the R2 heat recovery vrf . I am looking to put in 7 of them in a hotel to do all the hot water I should get 12.5 KW from each one with temps up to 70C but does it work as have only had feedback from mitsi own canteen ?

[mad fridgie]

Hi Us iceman,
can give you 85C water no problem, (design unit for dairy CIP cleaning the milk pipes!), can get partial steam, but the vapour gets trapped in the heat exchanger, head pressure becomes uncontrollable! Continuus running we can achieve mid 90C with occassional steam bubbles.
This unit for the dairy farms can have an effective COP of just under 10, in most cases around 7
Copeland scroll within normal operating envelope

[cooper3305]

Could anybody explain the effects of a low temp around -2degc ground source loop on a hp (r410a) running in heating mode? will the condenser/source heat exchanger have slugging refrigerant if the TXV is undersized? I have considered changing the superheat setting but as this is an extreme seasonal problem i am hoping for some insperation.

[GreenCool]

Hi Guys,

Probably far bigger than you were interested in but this graphic is of an ammonia heat pump being designed for a city in Norway.

>14MW heating from 60C to 90C, by cooling down the Fjord!

search youtube for

star-drammen-heatpump

hot stuff

all the best

GC

[desA]

Very nice...

[DEVIL]

Take a look at daikin new altherma (trying to kick mitubishi's but for the zubadan no offense to "VRVIII" ) i don't know it it's released yet but you might find some info they say it is going up to 80 deg C i think it's 2 stage like the mitsubishi VRF "booster unit" (2 stage, one stage from the VRF system and another compressor in the unit for the second stage)that delivers up to 70 deg C water temp.

I had the idea for doing this some time ago as i design heat pumps, but i did not see the need for such a hight condensing temp

[anup]

Hello Iceman,
Did you make any progress in these heat pumps? We have enquiries for high temp ASHP.
One possible application for high temp ASHP for power generation.
By using Organic Rankine Cycle engine (ORC), even at 85C temp, ORC generates power with an efficiency of 15-17% and you get by-product of hot water at 55-60 deg. C

[Aper Willy]

FACTSHEET 14 / 15: RESTWARMTE AARDAPPELVERWERKENDE INDUSTRIE

Verdamper 8 bar / 70°C
Condensor 13 bar / 90°C
Elektriciteit
Compressor
Van
Blancheur
Naar
Blancheur
Restwarmte
Retour
Restwarmte
Aanvoer
85°C
77°C
80°C
75°C

Meerjarenafspraken Energie-efficiency

14. Hoge-temperatuur
mechanische warmtepomp

De aardappelverwerkende industrie kampt over
het algemeen met een overschot aan restwarmte.
Een mogelijke toepassing hiervoor is
het opwaarderen van restwarmte naar een
hogere temperatuur. Bij een hoge-temperatuur
warmtepomp wordt de graad van restwarmte
verhoogd middels een medium. Het werkmiddel
wordt in een verdamper verdampt met behulp
van restwarmte. Een compressor verhoogt de
druk, waarna de warmte op hogere tempera-tuur
wordt afgegeven in de condensor.

Werkmiddel

Conventionele werkmiddelen zoals ammoniak zijn ongeschikt voor warmtepompen op een temperatuur boven 70 °C omdat de druk te hoog wordt: ammoniak heeft bij 90 °C een verdampingsdruk van circa 50 bar. n-Butaan heeft bij 90 °C een acceptabele druk
van 13 bar, waardoor dit werkmiddel wél geschikt is voor toepassing in hoge-temp warmtepompen. n-Butaan is echter licht
ontvlambaar; de installatie moet dan ook in een aparte ruimte geplaatst worden.
Een n-Butaan warmtepomp kan werken met een condensortemperatuur van max. 110 °C.

Compressor

De belangrijkste component van de hogetemperatuur warmtepomp is de compressor.
Deze vergt hoge investeringskosten, verbruikt uiteraard elektriciteit en heeft jaarlijkse
onderhoudskosten. Hierdoor vallen de netto besparingen lager uit.

Elektriciteitsverbruik

Voor een verdamperdruk van 8 bar (70 °C) en een condensordruk van 13 bar (90 °C) komt de COP overeen met 11. Dit verlangt een
besparing van 0,75 kWh elektriciteit per Nm

3.

Bron restwarmte en gebruikers

Om een redelijke efficiëntie te halen moet de temperatuursverhoging niet al te groot zijn.
Met restwarmte van 80 °C kan een proces verwarmd worden tot ongeveer 110 °C.

De belangrijkste gebruikers zijn: blancheurs

Mogelijke bronnen van restwarmte zijn:

•

Afblaas stoomschillers

•

Bakdampen

•

Rookgassen stoomboiler

Opmerkingen

•

Door de flinke investeringen is een hoge-temp
warmtepomp meestal alleen rendabel voor grotere vermogens.

•

Naast de investering in de installatie om de restwarmte op te waarderen, moet er vaak ook worden geïnvesteerd in de terugwinning van restwarmte.
Hierdoor vallen de investeringskosten hoog uit.

•

De hoge-temperatuur mechanische warmtepompnis een nieuwe toepassing die marktrijp is, maar nog niet is toegepast in de praktijk. Daarom zijn er subsidiemogelijkheden die max. 40 % bedragen van de meerkosten ten opzichte van de gangbare technieken.

Kengetal len

•

COP 11

•

Elektriciteitsverbruik 0,75 kWh/ Nm³

•

Restwarmte > 75 °C

•

Benodigde temperatuur < 90 °C

Informatiepunt SenterNovem

(tussen 9:00 - 12:00 uur en 14:00 - 16:00 uur)
Telefoon 030 239 35 33
E-mail info@senternovem.nl
Internet www.senternovem.nl/mja

REKENVOORBEELD

Aangezien hoge-temperatuur warmtepompen vooral geschi k t z i jn voor grotere i n stal l a t i es, wordt er gerekend met de warmteterugwinni ng voor b l ancheurs van twee 10 ton l i jnen.
Er i s voldoende warmte beschi kbaar op 80 °C.

U i t g a n g s p u n t e n :

•

Li jncapac i tei t 2 * 10 ton per uur

•

Vermogen b l ancheur 2 * 950 kW

•

Temperatuur b l ancheur 80 °C

O n t w e r p

•

Condensor 90 °C / 13 bar

•

Verdamper 70 °C / 8 bar

•

COP 11

•

Benut t ing restwarmte 1.727 kW

B e s p a r i n g e n

•

Aardgas 1 .250.000 Nm³

•

El ekt r i c i tei t - 934. 000 kWh

•

Net t o bespar ing € 228. 000

•

Invest eringskosten € 1.215.000

•

Terugverdi ent i jd 5, 3 jaar

De meer jarenafspraken energie -ef f ic iency (MJA’s) z i j n
overeenkomsten tussen de min ister ies van Economis che
Zaken (EZ), Landbouw, Natuur & Voedselkwali tei t (LNV) ,
Vol kshuisves t ing, Ruimtel i jke Ordening & Mi l ieubeheer
(VROM) , bedr i jven en inst e l l ingen ove r het e f fect ieve r en
e f f iciënt e r inzet ten van ene rgie.

Publ i c a t i enummer : 2MJAF0732 • augustus 2007

n-Butaan als 2de trap ziet er wel goed uit.

[Plank!]

A bit bigger than the OP asked for but many of you may find this interesting...

http://www.star-ref.co.uk/star/image...ian%20Army.pdf
http://www.star-ref.co.uk/star/image...20Neatpump.pdf

Smaller CO2 option - chilling and heating in one unit...

http://www.star-ref.co.uk/star/image...0Envitherm.pdf