Thermodynamic Panels & a heat store or heat recovery system

Looking at one of the Thermodynamic Panel system PDFs:

One set up has a thermal store (a tank that heats up, and your heating is delivered by coils that go into this store, heat up and take that hot water to where you want it), and a second, linked to a pool seems to have a form of heat recover system, in that the colder water from the pool is going back in the loop for re-heating via the Thermodynamic panels and the thermal store tank.

 

For the thermal store the Akvaterm thermal store water tanks looked good at the 2012 Eco Expo in London.

  •  The Akvaterm Akvantti thermal stores are oblong which could be a better shape for the plant room. It’s available as 1400lt, 2000lt or 2400lt volumes. The 1,400 litre unit is £3,757.00 + £85 carriage.

Akvantti-Accumulator-Heat-Store-Tanks-4

 

A chunk more information on the concept and benefits of a thermal store (and their version of one) at http://www.greenspec.co.uk/thermal-storage.php:

Thermal storage – pros & cons

+ Provides effective buffering
+ Reduces boiler cycling
+ Allows for integration with low temp heating systems eg underfloor
+ Adds mains pressure to hot showers
+ Provides potable hot water
+ The use of a heat exchanger means that in most cases, thermal stores can be integrated with existing pressurised boiler circuits
+ Requires much smaller cold water tank then standard vented systems
+ Thermal storage is recognised by NHER software
– Heat can be lost through inefficient heat exchangers
– Storage temperature will usually have to be 10 deg C higher than required DHW temperature
– Cannot be used with existing DHW power showers and pumps
– Expensive and unvented storage, very expensive
– Vented stores require a header tank to be located above the heating systems

Points to consider when specifying a Thermal Store

  • The design of the heating system should be matched to the calculated peak heat load.
  • When including solar heating, ensure that there is extra capacity within the store to accommodate fluctuations.
  • Where a biomass boiler is being used, consider sizing the store to provide for the heat capacity generated in a load / firing
  • Consider designing not only for short-term anticipated capacity but possible future extensions to the system.
  • Consider stratification of water temperatures within the store, particularly where low-grade heating is provided. Effective separation between the hot water at the top of the tank and the cooler water at the bottom, can increase the time between charges.
  • Ensure that there is adequate insulation to the store (100mm + PU foam)
  • Ensure that there is adequate pipework insulation

 

Some more Thermodynamic panel info

From a discussion on http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=9511&page=1#Item_15

Gary

I consider these as a form of air source heat pump, without a fan or finned coils. The underlying technology is well established and should be as reliable as a GSHP.

The panels are a good solution for a marine environment – I wouldn’t use ASHP units near the sea as the coils rot after about 7 years due to salt corrosion, so they would be a cheaper alternative than GSHP for such areas.

I have seen a completed installation and the owners were very happy with it.

Solar thermal it ain’t however – there is an improvement in COP when the sun is shining but it won’t provide free energy.

Chris

As far as I can find there are two manufacturers of these systems, the best known being Energie in Portugal http://www.energie.pt/ but also a company called Energy Panel in Spain. http://www.energypanel.es/productos.aspx?idFamilia=1&idProducto=1

The problem I have with them is a seeming lack of independent verification of their claims for running costs. I’ve seen mention of various installations being independently monitored but all my previous efforts to get these reports have so far failed.

Does anyone know of any such independent verification?

Some updated Thermodynamic heating system info

I’ve come across the GreenServeUK website with new info on the Thermodynamic Panels.

There’s a big FAQ at http://www.greenserveuk.com/faq/

How it works from http://www.greenserveuk.com/thermodynamics/how-they-work/

Step One

The environmentally friendly refrigerant liquid is fed into the veins of the solar collector.

This refrigerant (R134A) has a boiling temperature of -25°C. The panel absorbs the heat from the environment and raises the temperature of the refrigerant.

The liquid absorbs the heat and it vaporises into a gas which increases the pressure.

Thermodynamic Panel Dimensions are h 800mm, l 2000mm, D 20m.
Each panel is about 8 kg.

Step Two

The hot gas is then passed through a compressor where the pressure causes it to heat further.

Step Three

The heated gas is then passed into the heat exchanger where the heat is transferred into the water cylinder.

Step Four

The cooling gas then passes through a valve reverting back into a liquid where it runs back into the panel where the process begins again.

The system is a solar domestic hot water system in which the solar loop operates on a similar principle of a heat pump.

It is composed of:-

  • An unglazed heat absorber  (1) with 3.20 m2 total aperture area.
  • An insulated,  hot water thermal store (200 l) (2)
  • A  thermoblock, which comprises the electrical powered compressor (5), the thermostatic expansion valve (7), the electrical heating element (4) and the controller.
  • Heat transfer fluid (refrigerant R134a)

The heat transfer fluid in the solar loop is the refrigerant R134a.

The refrigerant is passing through the absorber and evaporates while collecting energy from the surroundings.

The evaporated refrigerant is sucked by the compressor which raises the pressure.

In the condenser, which is integrated as an immersed solar-loop heat exchanger in the lower part of the store, the refrigerant condenses while transferring its condensing heat to the domestic water in the store.

Before the refrigerant is returning to the absorber, a thermostatic expansion valve is reducing the pressure.

An electrical heating element is located in the lower part of the store at the height of the solar-loop heat for use in emergencies and for the anti-legionnaires system.

The magnesium anode (8) or sacrificial anode will extend the life of the tank.

 

Thermodynamic installed at Maidstone UTD Football Club

Just got this press release:

Thermodynamic installed at Maidstone UTD FC…
Project: Maidstone United Football Club – Gallagher Stadium
Client: Graham
Contractor: Gallagher / Greenheat

Thermogroup UK recently supplied two Thermodynamic systems, an Eco 2000 and an SB 24 to meet 100% of the hot water demand for showers and underfloor heating at the new home of Maidstone United FC.

MUFC were attracted to Thermodynamic because of the environmental factor and the potential savings possible against the originally specified electric heating system.

Thermodynamic panels at maidstone united

 

It was estimated that a 24 panel system, to provide underfloor heating to the clubhouse, would use a minimum load of 4.2kW of electricity. Based on this figure and assuming the system is used for an average of 5 hours a day, it is estimated that the SB 24 at MUFC will cost £2.10 per day or £766 per year to run (at £0.10/kW per hour).

The SB24 at MUFC is expected to have a payback of around 5.5 years and bring about an annual saving of £3000 when compared to the electric system that was originally specified.

Please note: The figures in this email are estimates only and we are in the process of installing energy monitors at MUFC to track the exact running costs, savings and payback period.

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UK Solar Hot Water Trial Findings

The Energy Saving Trust did a survery on a large number of UK and Republic of Ireland solar hot water systems.

PDF report on the survey >>

Key Points

  • There were 54 flat-plate systems in the trial.
  • There were 34 evacuated-tube systems in the trial.
    • There was no difference in the annual solar energy yield observed between solar installations using flat-plate solar collectors and those using evacuated-tube solar collectors. This may be because although evacuated-tube collectors have higher insulation, flat-plate solar collectors generally have a larger working area as a proportion of the collector size.
So there are none of the “new” Thermodynamic Panels in the survey. These do appear to be different and better. Providing 24 hour hot water.

Distribution of the surveyed / trial locations:

So for Silver Spray in Cornwall, should get better results as more sunshine:

The solar energy input to the hot water cylinder is at a maximum in summer, with back-up heating providing more energy in the winter months.

It’s key to set the backup (non solar) heating system to run so that the solar heating can be most effective and the house occupants have hot water when desired.

How to improve the performance of a solar water heating system:

  • Using boiler timers and/or solar controllers to ensure that water is only heated by the back-up heating sources after the water has been heated to the maximum extent possible by the sun.
    • Timing of back-up heating and hot water use. Systems
      provided more energy when the back-up heating was
      used just before the main hot water use or at the end of
      the day. This provides a better opportunity for the solar
      collector to heat the water rather than using the back-up.
  • Having an adequately sized dedicated solar volume (that is, a portion that can only be heated by the solar water heating system). Where a dedicated solar volume is not used (for example in systems that do not require the existing cylinder to be changed), the timing of back-up heating has a particularly important impact on performance.
  • Insulation is a vital part of this, as systems with poorly insulated storage cylinders can suffer from inadequate hot water provision in the mornings.

Key Findings:

  • Well installed and properly used systems can provide around 60% of the years hot water.
    • Across the whole trial, the proportion of domestic hot water energy provided by solar power ranged between 9 per cent and 98 per cent (with a median of 39 per cent).
  • Plenty of other findings, see the report.

Customer / Consumer Advice

What to expect from your installer:

  • All MCS installers should be able to provide a detailed breakdown of the specification and costs of their proposed system. They should:
    • Complete a technical survey.
    • Explain how they calculated the size of the system to be appropriate for your hot water usage.
    • Provide an estimate of how much heat will be produced by any proposed system.
    • Supply clear, easy-to-understand and detailed information and advice on how best to use the system and operating instructions.
    • Explain how the system will be installed and if there will be any disruption to your property.
    • Install and set controls and settings to ensure you get the most out of your solar water heating system.
    • Provide clear and easy-to-understand information on product and workmanship warranties.

EcoBuild: Thermodynamic Panels (Heat Exchanger)

Thermodynamic Panels

These black panels were on display:

http://www.thermogroupuk.com/thermodynamic.html

These black aluminium panels have refrigerant fluid pumped into them. The heat absorbtion of the black panels changes this to a gas, that is sent to a compressor, which releases heat energy in the heat exchanger where the heat goes into the water. The gas then goes through an expansion valve, putting it back to a liquid before it goes back to the panel. (See explanation & figures below forum comments below).

Claims:

  • 55 degree C water output.
  • Can provide 100% of hot water and heating, 24/7, 365 days a year.
  • Works day or night, as it absorbs heat energy from the atmosphere. It is presumeably helped when it’s sunny !
  • Works when temps are down to -15 degrees C
  • Can be wall installed, which would work well for the Silver Spray proposal.
  • Co-efficient (COP) rating of 4.5 to 7.
  • Distributed by Jewson.
  • 1 panel system (with the boiler and reverse refrigeration bits) is about £4,500.
  • Can have multiple panels in a “toast” stack. Expo figure for that was about £6,500.

Forum Comments:

http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=7740&page=1#Item_0

  • “Looks like it’s a heat pump with a solar-assisted air to liquid heat exchanger on the outdoors end.” seems to sum it up pretty well !
  • “depending on the heat pump, it’ll be better (better COP) than an ashp in sunlight, but probably worse at night unless there’s much wind to move air across it, although it will have a bigger surface area than in most ASHP’s which will compensate for this to some extent. “
  • “It also has the advantage of not needing (potentially noisy) fans”

Also from the forum, from their N. Ireland distributor:

The system is not new technology; it is basically a freezer “in reverse” and like a freezer consists of a heat collecting panel(s), refrigerant piping and an integrated electric heat pump.  It is a clever application of well tried and tested technology that has been around for almost 100 years.  The panels are made from weather protected anodized aluminium and are not vulnerable to extremes in hot or cold. They are light, weighing only 8 Kg and may be mounted in virtually any orientation or angle.  It has been estimated that 25% of the energy absorbed by a panel comes from solar irradiation, the balance taken from air and rain. Both sides of the panel are available to collect energy. The company that manufactures the system is based in Portugal and to meet growing global demand they have just built a second factory reflecting their 25 year history of success with the product.

You can check them out at http://www.energie.pt/?cult=uk

The Energie system is fully scalable from 1 – 2 panels for domestic hot water, to 4 – 24 panels for central heating right up to 40 panels for large volume hot water requirements. Note that additional panels simply mean faster water heating times, not higher water temperature which is set to between 55 and 60 C maximum.  A typical domestic installation for domestic hot water will have a 250L cylinder with a single panel mounted on the roof.

The heat pump is integrated directly into the Energie cylinder so an existing hot water cylinder cannot be used in this configuration. For central heating and large volume hot water requirements the heat pump (Solar Block in Energie speak) is a stand-alone device. Energie cylinders are either stainless steel or enamelled steel and can come with an additional coil for connecting into a backup heat source if desired. Sizes range from 200L to 6,000L.

All Energie Thermodynamic Systems are accredited under the MCS scheme.

The system uses 407A refrigerant and doesn’t need topping up. The only maintenance may be the occasional replacement of the sacrificial anode in the cylinder should you live in an area with soft water.

Another point raised concerned the panel frosting over in winter. This is possibly best addressed by personal experience.  I installed a 300L single panel system in my home at the start of this year, and although there was some frosting in the very cold weather at that time on the top surface of the panel, the bottom side was clear, and we always had enough hot water. Eight months later we have never had call to revert to either our central heating boiler which has been turned off these past 5 months, or the small integrated immersion that comes with the Energie cylinder. I estimate from measurements I have taken that the Energie system has used an average of 3.6 KWh of electricity per day over the 8 months January to August for our 4-person household at a COP of just over 3.

Hundreds of Energie systems have been installed successfully throughout Ireland over the last 4 years and having come through last winter are well tested for the vagaries of the UK and Irish climate.

Finally some additional information as supplied by Energie can be found using the link below. http://www.e3renewables.com/downloads/

More Information from ThermoGroup

From:

www.thermogroupuk.com/thermogroup_pdfs/Thermodynamic%20Technical%20Information.pdf

1. Aluminium Panels
Refrigerant fluid circulates through the panels and absorbs heat energy from the atmosphere. This increase in temperature changes the fluid into a gas.

2. Compressor
The gas then passes through a compressor and the temperature increases.

3. Hot Water Cylinder
The hot gas then flows through a heat exchanger in the Thermodynamic Block which transfers the heat into the water, which can be used for sanitary hot water, space heating or larger applications such as swimming pools.

4. Expansion Valve
The gas then passes through an expansion valve, reverts back to a liquid and flows back to the panels to
repeat the process.

Figures for Thermodynamic Atmospheric Energy Panels

I read or heard at the show, that increasing the number of panels increases the speed at which the system works. So I think you could add a panel to make the system work faster at grabbing the optimum conditions? (Need to ask them)

Air Source Heat Pump Vs Thermodynamic Atmospheric Energy Panels:

 Air source heat pumps  Thermodynamic
• COP of around 4
• Outputs of 6-18kW
• Outdoor noise pollution
• Requires regular maintenance
• Efficient to just below 0 degrees C
• Fixed sizes
• Fan assisted, low active surface area
• COP of up to 7
• Outputs of 1.7 – 53 kW
Silent outside
• Only one moving part
• Works down to -15 degrees C
• Total flexibility
• Active surface area of 3.2m2 per panel
 Standard Solar Thermal Panel  Thermodynamic
• Provides up to 70% of your hot water
• Must be mounted south facing for best results
• Needs backup from a boiler or immersion heater
• Needs sunlight – low performance in winter/night
• Can only assist central heating
• Fragile glass panels
• Provides up 100% of your hot water.
• Can be mounted south/west/east/north on a wall
• No backup required – Not connected to boiler
• Works in the dark and down to -15OC – 24/7
• Can provide 100% of your central heating
• Aluminium – tough, long lasting, anti corrosive
They can work on a north facing wall, but work best the more direct solar exposure they get.

Case Studies and Cost

Running Cost:

From www.thermogroupuk.com/thermogroup_pdfs/Thermodynamic%20Case%20Studies.pdf:

  • 4 bed house, one panel & 280 L cylinder, for hot water only = £109.50 pa
  • 3 bed house, 6 panels & thermodyanmic block for central heating only = £346.75 pa

So how much would a central heating and hot water system cost per annum ?
– those figures have an assumed electricity tariff of £0.14/kWh. If the system is part driven by my own solar panels, the cost would be reduced (although you need to factor in the capital cost of the solar panels.)

Purchase Cost:

Need to add in the cost of having it all installed and signed off to the level that’ll hopefully get the Renewable Heat Incentive.

From www.thermogroupuk.com/thermogroup_pdfs/Thermodynamic%20Kit%20Retail%20Prices.pdf

Thermodynamic kits ship pre-gassed, ready for installation and include the following:

  • Thermodynamic Panels/s
  • Panel Fixing Kit
  • Hot Water Cylinder with Thermodynamic Block
  • 30m Copper Pipe
  • 30m Low-loss Lagging

The above thermodynamic kits are suitable for supply of sanitary hot water in domestic applications. Thermodynamic systems for Ambient heating or larger applications require a more detailed specification to ensure we provide you with the right solution.

I’ve emailed them for a rough quote.