EU Air Handling Units with SEMCO EXCLU-SIEVE

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Mary Stephens
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1 EU Air Handling Units with SEMCO EXCLU-SIEVE

2 The acquisition of US based Semco has given us the opportunity to include a new range of rotary heat exchangers in our EU air handling unit range. Hygienic Hygroscopic wheel with molecular desiccant coating, which avoids contaminant carryover. Only water moisture is transferred. Compact Rapid absorption of moisture gives a high latent efficiency even at high efficiency Efficient High latent efficiency means good transfer of water moisture Low Operating costs The excellent cooling recovery saves energy, improves indoor climate and reduces the size of the chilled water plant Good winter performance In cold climates, the high latent efficiency reduces frosting and allows the wheel to run at lower temperatures, which means more energy can be recovered. Corrosion protection Ceramic pre-coating gives extremely good corrosion protection. Non-wearing seals Labyrinth seal effectively suppresses bypass air leakage without contact with the surface of the wheel. Robust casing Stiff and strong wheel casing avoids deflection and leakage of air. The EXCLUSIEVE wheel utilizes a 3Å molecular sieve desiccant coating to limit the risk of desiccant cross contamination, which would otherwise cause a portion of the exhaust air pollutants to be transferred, along with the water vapour, to the fresh air stream. The 3Å molecular sieve material utilized by SEMCO was developed specifically for "selective adsorption" and has been successfully used for decades by the petrochemical industry. Other desiccants like silica gel and oxidized aluminium cannot provide selective adsorption, which means that when used on a rotary heat exchanger they transfer not only water but also other substances and thus reduce the quality of the supply air. Molecular sieves are able to absorb substances with a molecular diameter less than that of itself. A 3Å molecular sieve has the interesting property of being able to absorb water molecules while excluding all others normally found, which means that contaminants causing smells, for example, are not transfered from the exhaust air to the supply air. The EXCLUSIEVE media is made from aluminium which is evenly coated, prior to being formed into its honeycomb configuration, with a dense layer of corrosion resistant desiccant. This extends the life of the aluminium media substrate and enhances its structural integrity. This is in sharp contrast to most other total energy wheels which are produced by oxidizing the surface of the aluminium substrate to form a crude desiccant, leaving the product susceptible to further oxidation and diminishes its structural integrity. Low maintenance drive system Variable or constant drives designed to operate in the tough environment and offer a long life with practically no maintenance

Non-wearing Extruded Labyrinth Seals EXCLU-SIEVE utilizes a four-pass labyrinth seal, which has been designed to give optimum performance under the pressure conditions encountered in this application.

3 Non-wearing Extruded Labyrinth Seals EXCLU-SIEVE utilizes a four-pass labyrinth seal, which has been designed to give optimum performance under the pressure conditions encountered in this application. Since the seals never actually touch the rotating surface, their life is indefinite. All seals are easily field adjustable. This efficient sealing system increases performance and virtually eliminates carryover of contaminants from the return air stream to the supply air Stream. Modular Media Sections with Aluminium Spoke Support System The media support system is made from aluminium extrusions. This provides the substantial structural backbone required to withstand the forces encountered during a wheel s 10,000,000 annual revolutions (assuming continuous operation). The use of aluminium drastically reduces the weight of the rotor when compared to a steel support system. The result is a more evenly balanced rotor, which reduces wear and tear on the drive system and bearings. The tolerances obtainable from an extruded media support structure allow for the flattest possible sealing surface. This adds significantly to the integrity of the total sealing system. Service Free Drive and Control System A responsive and maintenance-free drive system is an integral part of any rotary heat exchanger. The drive system standard with any EXCLU-SIEVE unit is an AC constant or variable speed system with drive belts.

4 SEMCO EXCLU-SIEVE enthalpy exchanger recovers both sensible (temperature) and latent (moisture) energy, and does so far more effectively than other competitive offerings. This performance edge is a result of EXCLU-SIEVE s unique transfer core. This honeycomb like media utilizes an aluminium substrate coated with a fast acting, 3Å molecular sieve desiccant. As the transfer core slowly rotates between the outdoor and return air stream, the higher temperature air stream gives up its sensible energy to the aluminium. This energy is then transferred to the cooler air stream during the second half of the revolution. Just as the temperature is captured and released, so is the moisture (latent energy.) This is accomplished by the desiccant coating of the wheel. The desiccant has a very strong affinity for water and an enormous internal surface area to bind the water on its surface. Since the opposing airstreams have different temperatures and moisture contents, their vapour pressures on their surfaces differ. This vapour pressure differential is the driving force necessary for the transfer of water vapour (See Figure 2.) The ability to recover latent energy is one of the major benefits of SEMCO s EXCLU-SIEVE technology. It will do this both in the cooling and the heating season. During the cooling season the outdoor air is dehumidified and pre-cooled. (See Figure 2.) This significantly reduces the cooling requirements of the conditioned space. In the heating season, the process reverses and the outdoor air is humidified and preheated. This reduces the costly humidification of ventilation air as well as the heating requirements of the indoor space. Latent recovery doubles the energy savings potential recognized with the use of the sensible-only technology. It allows for cuts in chiller and boiler capacities. System designs incorporating total energy recovery are first cost equivalent to conventional designs when achieving the same ventilation requirements and supply air conditions. In addition, they provide operating cost savings year-in and yearout.

5 Tubular Steel Casing Construction To avoid deflection of the energy wheel casing due to the significant torque imposed by the air pressure on the energy wheel surface, a tubular steel framework is used. Casing deflection is undesired since it increases the gap between the seals and the wheel surface causing excessive air leakage. Built-in Bearing Replacement System The bearings used in the EXCLU-SIEVE units provide a long life with minimal maintenance. The external pillow block bearings simplify any replacements should this ever become necessary. The rotor remains in the casing and none of the rotor or media has to be removed.

6 Selection procedure 1. Find a wheel size from the chart below 4. Find the efficiency of the wheel from the chart below. Efficiency chart Efficiency Qmin/ Qmax Calculate the air velocity for each of the airstreams (supply and extract) using the area given in the table below. Face velocity m/s 5. Find the pressure drop for each side in the chart below EURU Wheel size (bb) Area m Calculate the ratio of the of the air flow rates: Qmin Qmax Pressure drop, Pa Pressure drop Air velocity, m/s

7 Selection procedure Calculate the conditions after the wheel: For the supply air X2 = X1 - es Qmin Qsupply (X1 - X3) Where X is temperature, moisture content or enthalpy

Purge volume As energy recovery wheel rotates from the exhaust air stream into the supply air stream, a small amount of the exhaust air is traversing the flutes of the wheel media as it passes by the

8 Purge volume As energy recovery wheel rotates from the exhaust air stream into the supply air stream, a small amount of the exhaust air is traversing the flutes of the wheel media as it passes by the seal separating the two air streams. If this volume of exhaust air were allowed to mix with the clean supply air stream, cross-contamination would occur. Cross-contamination is virtually eliminated by a purge section, which is an integral part of the casing design. The purge section utilizes the pressure difference which exists between the outdoor and return air streams to purge the transfer media with clean outdoor air prior to its rotation into the supply air stream. Figure 7 provides a graphic representation of the purge section operation.

9 Odours and contaminants The EXCLU-SIEVE product was specifically developed for applications involving contaminated air streams. Its field adjustable purge section and four pass non-wearing labyrinth sealing system limits air stream cross-contamination to less than.04 percent of the exhaust air concentration by volume. Selective adsorption, the ability to transfer water vapour to and from the exhausted air stream while allowing other gaseous contaminants to pass unadsorbed, is a necessity for most all energy recovery applications. Re-circulating some portion of these contaminants back to the space is undesirable since it reduces the dilution ventilation efficiency (requiring more ventilation air), can cause buildup of odors and, in some applications, result in an unhealthy environment. The EXCLU-SIEVE wheel provides selective adsorption through the application of a 3-angstrom molecular sieve desiccant material. Desiccants such as silica gel, activated alumina, oxidized aluminum, and even other types of molecular sieves, do not provide selective adsorption. Adsorbents trap water vapor and/or other components within their complex internal surface area, which is comprised of a network of holes or pores. Molecular sieves are different than all other desiccants. Their pore diameter is completely uniform and in the case of a 3Å molecular sieve, it can be controlled to precisely 3 angstroms. This configuration excludes the adsorption of molecules that have a kinetic diameter greater than 3 angstroms (practically all contaminants) while having a strong affinity for and adsorbing water vapour (2.8 angstroms).

10 Ordering Semco TE3 Rotary Heat exchanger Supply air unit size (aa) 22,32,33,42,44,53,64,73,82,84 Semco rotor TE size (b) 5,9,13,24,35,43,46,56 Purge index setting (c) 1-9 (From Acon) Arrangement (d) 4 = Arangement D, supply air under Motor type (e) 1 = 230V, 1 phase, 50 Hz, variable speed with inverter Temperature controller (f) 1 = 24V with 4 point Sensors 3 = 24V with Averaging Sensors Rotation detector (g) 1 = 24V, singe phase Wheel treatment (h) 1 = Anti stick coating Casing materials (i) 1 = galvanized steel sheet Design variant (j) Inspection side (k) 1 = right hand inspection 2 = Left hand inspection EURU-aa-bb-c-4-1-f j-k Prices: available in Acon include transport from USA to Jönköping and import duties. Delivery time: available in Acon Wheels will normally be shipped to Jönköping for distribution together with AHU

11 B L D A C EURU EU size (AA) Wheel size (bb) A B L C D Diam

We Bring Air to Life FWG - EU with SEMCO EXCLU-SIEVE GB 2011.08-9110 Copyright 2011 Fläkt Woods Group Fläkt Woods is a global leader in air management.

12 We Bring Air to Life FWG - EU with SEMCO EXCLU-SIEVE GB Copyright 2011 Fläkt Woods Group Fläkt Woods is a global leader in air management. We specialise in the design and manufacture of a wide range of air climate and air movement solutions. And our collective experience is unrivalled. Our constant aim is to provide systems that precisely deliver required function and performance, as well as maximise energy efficiency. Solutions for all your air climate and air movement needs Fläkt Woods is providing solutions for ventilation and air climate for buildings as well as fan solutions for Industry and Infrastructure. Air Handling Units (AHUs) Modular, compact and small AHU units. Designed to ensure optimisation of indoor air quality, operational performance and service life. Air Terminal Devices and Ducts Supply and exhaust diffusers and valves for installation on walls, ceiling or floor are all included in our large range and fit all types of applications. Chilled Beams Active induction beams for ventilation, cooling and heating, and passive convection beams for cooling. For suspended or flush-mounted ceiling installation and multi-service configuration. With unique Comfort Control and Flow Pattern Control features. Residential ventilation A complete range of products for residential ventilation. Consists of ventilation units, exhaust air fans and cooker hoods designed to optimise indoor comfort and save energy. Fans Advanced axial, centrifugal and boxed fans for general and specialist applications. Comprehensive range including high temperature and ATEX compliant options. Engineered for energy efficiency andminimised life cycle cost. Chillers Air-cooled and water-cooled chillers with cooling capacity up to 1800 kw. Designed tominimise annual energy consumption in all types of buildings. Controls and drives Variable speed drives and control systems, all tested to ensure total compatibility with our products. Specialist team can advise on energy saving and overall systemintegration. Fläkt Woods Group SA 18, avenue Louis Casaï, CH-1209 Geneva, Switzerland Tel info@flaktwoods.com See global web site for international sales offices

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