# Energy From Thorium Discussion Forum

 It is currently Sep 23, 2018 1:16 pm

 All times are UTC - 6 hours [ DST ]

 Page 2 of 2 [ 21 posts ] Go to page Previous  1, 2
 Print view Previous topic | Next topic
Author Message
 Post subject: Re: Very high temperature heat pumpsPosted: Feb 28, 2016 1:06 pm

Joined: Jul 14, 2008 3:12 pm
Posts: 5045
How about aluminium chloride for the working fluid?

Top

 Post subject: Re: Very high temperature heat pumpsPosted: Feb 28, 2016 3:56 pm

Joined: Jun 19, 2013 11:49 am
Posts: 1552
Problem is that anhydrous aluminium chloride reacts non reversibly with water. How about elemental iodine?

Top

 Post subject: Re: Very high temperature heat pumpsPosted: Apr 06, 2016 3:03 pm

Joined: Jun 05, 2011 6:59 pm
Posts: 1335
Location: NoOPWA
Folks, the working fluid does not have to condense. Think Brayton vs Rankine cycle. Indeed, an acoustic heat pump might work famously.

_________________
DRJ : Engineer - NAVSEA : (Retired)

Top

 Post subject: Re: Very high temperature heat pumpsPosted: Aug 06, 2016 12:59 pm

Joined: Jun 19, 2013 11:49 am
Posts: 1552
Having stumbled across a discussion of transcritical carbon dioxide heat pumps on the internet in the context of domestic heat pump equipment I decided to see what would happen if a transcritical steam cycle was used.

We assume 285°C steam at ~70 bar. It has enthalpy of ~2900kJ/kg.
Compression of the steam to ~580 bar yields a supercritical water fluid of ~904K. This process consumes ~530kJ/kg, so ~590kJ/kg at ~90% compressor efficiency.
580 bar, 630°C steam has an enthalpy about ~3400kJ/kg.

This is fed to the gas cooler which I assume will be some for of printed circuit heat exchanger given the pressures and temperatures involved.
Constant pressure heat capacity of water is about 2kJ/kg.K
Normal design practice is to get the biggest possible delta-T on the high temperature leg, so we would seperate out heat for several temperature ranges.

The top range will be 500°C to 630°C, which would be suitable for various petrochemical and similar processes, enthalpy would drop to 2600kJ/kg at 500°C - which results in the extraction of 800kJ/kg of heat to the heat exchanger.

The middle range will be 400°C to 500°C, I envisage this being used for heating of TOSCOAL type retorting processes and similar pieces of equipment that can require active temperatures of ~480°C from steam circulating in the reactor. Enthalpy will drop to roughly 1850kJ/kg. Releasing 750kJ/kg in this temperature range.

Finally the 'bottom' range is ~270°C to 400°C, enthalpy drops to ~1200kJ/kg, releasing 650kJ/kg. I am not entirely sure what this temperature range could be used for, but I am sure our industrial colleages could find something useful.
The fluid is then an effective liquid and can thus be throttled down to 70atm through a simple pressure regulating valve with minimal loss of temperature and enthalpy, whereupon it can be used as feedwater for the reactor, indeed it is higher temperature than most feedwater and can assume a significant portion of the reactor feedwater duty.

So the net effect is:
1700kJ of reactor heat and 590kJ of compressor power will produce:
800kJ from 500°C to 630°C.
750kJ from 400°C to 500°C
650kJ from 270°C to 400°C

Net effect is 1700kJ reactor heat and 590kJ of compressor power to ~2200kJ of heat at higher temperature.
1700kJ of reactor heat is equivalent to 595kJ of electrical power, so effectively 1185kJ of power is converted to ~2200kJ of high temperature heat.

Effective COP is 1.86.
I would have to do some proper calculations rather than this semi-idealised model, but it seems there is some potential here after all, although a 580 bar steam compression cycle seems rather difficult to engineer.
I will also develop a recuperated cycle

Top

 Post subject: Re: Very high temperature heat pumpsPosted: Aug 08, 2016 4:37 am

Joined: Sep 02, 2009 10:24 am
Posts: 511
Quote:
Effective COP is 1.86.

By "effective" you mean after the inefficiencies?

I think that's a good result if we want to electrify a process - obviously beats resistance heating.

At the moment though it has to compete with co-fired gas, so gas -> heat -> electricity -> heat, gives an efficiency max of 60% x 1.86, which makes it probably not worthwhile yet.

Top

 Post subject: Re: Very high temperature heat pumpsPosted: Aug 08, 2016 5:39 am

Joined: Jun 19, 2013 11:49 am
Posts: 1552
This is not like a conventional heat pump cycle - as the heat source used could be used to generate electricity.
It is the effective COP after compressor inefficiencies if we assume the alternative is all the input steam is fed to a turbine and used to generate electricity for resistive heat.

Top

 Display posts from previous: All posts1 day7 days2 weeks1 month3 months6 months1 year Sort by AuthorPost timeSubject AscendingDescending
 Page 2 of 2 [ 21 posts ] Go to page Previous  1, 2

 All times are UTC - 6 hours [ DST ]

#### Who is online

Users browsing this forum: No registered users and 1 guest

 You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum

Search for:
 Jump to:  Select a forum ------------------ General Nuclear Discussion    Forum Policies and Posting Help    General Discussion    Political, Industrial, Organizational Developments    Safety, Security, Proliferation    Reprocessing, Transmutation, Waste Storage    Thorium in the News    United States    Canada    Europe    India    China / ASEAN / Korea / Japan General Energy Discussion    Energy Issues and Technologies Registered Discussion    Registered Discussion    Conferences and Public Education Liquid-Halide Reactors    Fluoride Reactor Design    Fluoride Reactor Processing    Chloride Reactor Design    Reactor Materials and Fluids    Power Conversion Systems    Reactor Dynamics and Control Solid-Fueled Reactors    Water-Cooled Reactors    Gas-Cooled Reactors    Liquid-Metal-Cooled Reactors    Salt-Cooled Reactors Thorium and Uranium Fuel Cycles    Uranium and Thorium Supply    Uranium Enrichment