A chill in the air

With a United Nations agreement promising to slash the use of hydrofluorocarbons (HFCs) in refrigeration and air conditioning systems by 85% by the 2040s, we have been covering the race to find a suitable replacement. This week, Simon Lamberton-Pine, Managing Director of DPAC UK, makes the case for a different kind of chiller...

'Absorption is the process in which a fluid is dissolved by a liquid or a solid (absorbent). Adsorption is the process in which atoms, ions or molecules from a substance (it could be gas, liquid or dissolved solid) adhere to a surface of the adsorbent. Adsorption is a surface-based process where a film of adsorbate is created on the surface while absorption involves the entire volume of the absorbing substance.' -  "Absorption vs Adsorption." Diffen.com. Diffen LLC, n.d. Web. 29 Dec 2016

Ok, so now the technical explanation is done, lets move on to why you should be considering the use of ADSORPTION, which is the main reason for writing this feature! But before that perhaps it would be better to look at the features, potential uses, and applications of the technology.

Adsorption causes molecules to adhere to a surface rather than add to
its mass, as in absorption

As a result of the recent HFC Phase out programme, there is heightened interest in environmentally friendly and sustainable alternatives to traditional chillers for cooling use in commercial and industrial applications. Most of these are already well known (absorption, CO2, propane, ammonia – among others) however probably the least well known is adsorption.

Adsorption equipment is only currently available from a handful of manufacturers, and therefore their individual product designs vary, however their principle of operation is the same. Adsorption chillers are ideal when used 24/7,  operate at high efficiency – even with variable loads, and also produce chilled water rapidly from start-up.

Chillers, which often have 25yr lives, will
be most affected by the new rules

An Adsorption chiller is a highly reliable, virtually zero maintenance, efficient solution that uses waste heat i.e. from CHP or Solar to produce chilled water, which can then be used for air conditioning cooling or connected for refrigeration applications. Adsorption technology produces chilled water down to as low as 3º C which is ideal for any application with a high cooling demand such as Commercial offices, Process cooling, Supermarkets, and Data centres.

The chillers can be used in applications where there is a waste heat source, i.e heat recovery off a process, Biomass Boilers, Solar Panels, District Heating or via a CHP process. These highly efficient chillers provide great cooling capabilities and uses water as its cooling agent, so it’s highly environmentally friendly.

With water as the refrigerant, any piping or valve installation can be undertaken easily as there are no hazardous substances such as lithium bromide or ammonia. The chillers have long life expectancies of 20-30 years and end of life disposal is easy as the chillers have no hazardous refrigerants to dispose of.

For more information on the above, watch these videos by SorTech AG on the Technology and Applications of adsorption chillers.

Adsorption chillers can cool buildings using their own waste heat, which
is idea for use in data centres

Primary advantages

• Adsorption chillers can deliver a substantial reduction in both primary energy consumption and carbon emissions.
• Adsorption chillers can operate efficiently with a lower heat source thereby delivering cooling solutions to a wide range of applications.
• Maintenance is kept to a minimum because the Adsorption chillers use such a simple process; the downtime is minimal with no potential crystallization issues associated with Absorption
• Long life cycle 20- 30 years of operation.
• Adsorption chillers can be utilized with dry coolers available in micro channel design from DPAC
• The are no hazardous substances within the chiller (i.e. HFC’s, lithium bromide or ammonia); it uses silica gel (a natural substance) and water as a refrigerant. Therefore, the whole process is highly environmentally friendly - right through to end of life disposal
• Additionally, our Sortech models are available in a variety of smaller capacities from just 10Kw, which can easily be connected. By coupling individual modules, projects can be applied up to a nominal capacity of 310 kW
• The cooling water evaporates in a vacuum and thereby extracts heat from its surroundings (evaporating-energy). Through this process, cooling takes place. There are no high voltage motors or large compressors and no special external temperature controls are required for capacity control or to protect the chiller

Adsorption chillers keep maintenance costs down by reducing the amount
of equipment required

UK based M&E Consultants, Contractors and FM Businesses should now be considering adsorption equipment as an alternative (particularly if they know of a project with waste heat availability) and in most cases, they are far more cost effective, being more efficient and with substantially lower running costs. Obviously, there are pros and cons to all types of cooling equipment and in particular to adsorption equipment, but one of the biggest pros is that adsorption equipment is available through the Government backed grant scheme, however there are some criteria that must be met before being considered. 

The Renewable Heat Incentive (RHI) is a UK Government scheme set up to encourage uptake of renewable heat technologies amongst householders, communities, and businesses through financial incentives. It is the first of its kind in the world and the UK Government expects the RHI to contribute towards the 2020 ambition of 12% of heating coming from renewable sources. The Renewable Heat Incentive has two schemes - Domestic and Non-Domestic. They have separate tariffs, joining conditions, rules, and application processes. 

The Non-Domestic Renewable Heat Incentive (RHI) is open to industrial, commercial, public sector and non-profit organisations with eligible installations in Great Britain. This includes small Businesses, Hospitals, Schools as well as district heating schemes where one installation serves multiple homes. To qualify for the non-domestic or commercial RHI grant the installation must supply renewable heat to an eligible load and be supplied by an eligible source.

Adsorption chillers work with renewable heat sources, such as
 water source heat pumps, so are eligible for grants

The RHI will support heat where that heat is used in a building for ‘eligible purposes’, for example, heating a space, heating water or for carrying out a process where the heat is used and the heat must be transmitted by water or steam. For a building to qualify for space heating it must be totally enclosed and considered permanent.

Process heating can be: the use of heat to carry out a specific process such as industrial cooking, drying (including drying of wood and other biomass fuels), pasteurization or chemicals manufacture. Other examples include heat that is used for cooling, e.g. passing renewable heat through absorption chillers. Eligible sources of renewable heat are, the air for air to water heat pumps and water, ground or recovered heat for ground source installations. Recovered heat must not exceed 2/5 the of the entire heat production.

For adsorption equipment, the important section for the RHI grant is the lower temperatures of adsorption machines working down to 50 degrees in association with Ground Source Heat Pumps and are therefore entirely suitable for RHI grants.

The renewable heat incentive is paid quarterly based on the measured amount of heat produced in the installation. Ground and water source installations attract a two-tier grant payment in the form of £0.0895 per Kw hour thermal for the first 1314 run hours per annum and £0.0267 for the remainder of the eligible heat production per annum. Air source installations attract a flat rate of £0.0257 Kw hour thermal per annum. The tariff levels increase each year currently matching the RPI inflationary index.