A dust storm or a sandstorm is a meteorological phenomenon caused by strong winds that occur in arid and semi-arid regions. The Sahara is considered to be a major source of such storms. In the region, such as the Arabian Peninsula, sandstorms are frequent, and not a single summer day is free of dust. Sandstorms can impede nearly all our daily activities. Figure 1: a and b (Kuwait City) illustrates the effect sandstorms have on visibility. But the relevant question to be asked in the HAVC sector is, what is the impact of sand storms on HVAC equipment?

COLLECTION MECHANISMS

To better understand the effect of sandstorms on the performance of air filters, it is important to highlight the common collection mechanisms at which particles get deposited on the fibre surface.
When the subject of air filtration is addressed, the first misconception that comes to mind is particles being strained between the clearances of two fibres due to its diameter. This mechanism is called “straining” and is not a dominant mechanism in depth filtration.

Another mechanism to consider is the impaction mechanism. It occurs when the inertia of a particle does not allow it to follow the gas streamlines and, finally, impacts the fibre surface and leaves the air stream. The impaction mechanism depends on the particle size, density of the dust, depth of the filter and the velocity of the air flow. Interception mechanism, on the other hand, occurs when a particle follows the streamline, but is attached to the fibre surface owing to its diameter. For particles of 1 µm and smaller, it is bombarded by air molecules (Brownian motion) and is captured on the fibre surface by diffusion.

Complex interactions that occur between Brownian diffusion and inertial effects result in the process called the Most Penetrating Particle Size (MPPS). The MPPS is defined as the particle size at which the filter efficiency is the lowest at a given flow rate. MPPS is only significant when dealing with absolute filters, such as HEPA and ULPA filters. The impaction, interception and diffusion mechanisms are illustrated in Figure 2.

Clearly, the filtration process cannot be achieved through a single stage. Fresh, pre-, fine and absolute filters constitute the major filtration stages used by HVAC designers to provide clean air into the indoor space.

Sandstorms increase the dust concentrations, challenging the filters in the Air Handing Units. Consequently, the life span of the air filter is shortened, which is not cost-effective. Such evaluated concentrations may cause bridging of particles to form dendrite, which is an example of dust cake agglomerates on the filter surface and, consequently, impair it from acting as depth filter, as shown in Figure 3. Surface deposition occurrence on a depth filter prior to the full utilisation of its thickness signifies that the depth filter is acting merely as a surface filter. In other words, the surface pores will strain particles larger than their diameter, as shown in Figure 4. Pre-filters play an important role in allowing fibrous filters to perform as depth filters. In fact, large particles can be easily removed by means of a pre-filter such as, a foam medium [Figure 5], which be regenerated by water wash.

When an air filter starts to collect dust particles, either within its depth and/or at its surface, the filtration behaviour becomes more complex to describe. Dust particles form a so-called dust cake, as they deposit on the filter medium. Subsequently, this layer of dust acts as another layer of filtration.

Dust cakes can be formed by a combination of two primary mechanisms – bridging and complete blocking. Bridging takes place when particles smaller than the pore sizes in the filter medium form a cake; this occurs when the particles are at a higher concentration at the feed. On the other hand, complete blocking is a sieving process that occurs when particles are larger than the pore sizes. Figure 6 shows HEPA filter preceded by a fine filter and coarse pre-filter, where, as a result, it is challenged with low-dust concentration, and smaller particle size and depth deposition has taken place. On the other hand, Figure 7 shows similar HEPA challenged with higher dust concentration and larger particles filter in the absence of a fine filter.

Surface deposition on a depth filter does not allow it to utilise its thickness and lower filters permeability drastically, which is inversely proportional with the pressure drop of the filter. In depth filtration, fine dust settles around the fibre and the changes in filter permeability are negligible, at least in the initial loading conditions. Consequently, the pressure drop response will also increase slowly, and the lifetime of the filter gets extended.

PLEATED FILTERS

To deal with high dust concentrations, the role of pleated filter in the given space is highlighted, which decreases the air medium velocity. The decrease in velocity translates into a longer aerosol’s residence time inside the filtration medium, which increases the probability of the particle-fibre contact. As a result, it leads to an enhancement of diffusional capture efficiency, leading to increased particle loading capacity per unit area, when compared with a flat sheet medium. Pleating filtration medium also enables an increase in the collection efficiency for a given pressure drop, provides higher dust holding capacity and reduces energy consumption.

A FEW RELEVANT QUESTIONS

The above discussion only gives a glimpse of the effect sandstorms can have on the HVAC systems. However, pertinent questions that need to be asked and answered are: How does being exposed to high dust concentration frequently affect our respiratory system? What is the physical and chemical composition of the suspended dust in sandstorms? What design modifications are HVAC designers willing to propose to deal with a high dust concentration climate? And finally, is filtration enough to solely combat sandstorms?

The writer is Regional Director, Middle East, and International Consultant, EMW Filtertechnik, Germany. He can be contacted at iyad.al-attar@emw.de.

LG Electronics

LG Electronics on March 23 unveiled its new Multi V III commercial air conditioner in the GCC, at Atlantis, The Palm, Dubai, targeting large-scale facilities, such as commercial buildings, office complexes, schools, mosques, residential buildings and retailers. The third generation of the Multi V series, the new air conditioner will be LG’s flagship product in the region, where demand for energy-saving technology is growing fast, the company said.

According to LG, the launch of the Multi V III is part of LG’s plan to secure $10 billion in global sales by 2014.

The company claimed that the Multi V III came with three key consumer benefits: higher energy efficiency, larger capacity and longer piping design. The increased piping length of 1,000 metres gave architects greater flexibility in locating the condensing unit, the company said.

LG has listed other product features and advantages:

• The V-Scroll inverter boosts the energy efficiency of the unit.
• The unit comes with a cyclone sub-cooling circuit.
• A new refrigerant distributor delivers a COP (coefficient of performance) level of 4.6 for heating and 4.3 for cooling.
• Its 16HP capacity per unit (with a maximum of 48HP with four connected units) and smaller space requirement makes it easier, more efficient and cheaper to install and maintain.

Referring to the new air conditioner, HS Paik, President, LG Electronics Gulf FZE, said, “As a company with a strong focus on producing energy-efficient products, we feel that the Multi V III addresses all the major HVAC requirements of businesses in the Gulf. With this product, we are in a strong position to work with our dealers and business partners in the region to make LG the leading provider of smart and efficient HVAC solutions.”

Mario Seneviratne, Managing Director, Green Technologies, FZCO, added: “LG is launching a more energy-efficient product line, which feeds into the sustainability and energy awareness programmes globally, thus making it easier for engineers, contractors and developers to achieve their environmental objective as well as reduce their operating costs.”

Flamco

Saying that air and dirt particles are a hazard to the functioning of heating and cooling systems, Flamco a Netherland-based company, has announced introducing what it claims to be a new technology in air and dirt separation. The patented Dual Zone Flow Diversion technology unites all existing techniques for separating air and dirt particles from the system water, the announcement claimed. Introduced for the Flamco Clean, Flamcovent and Flamcovent Clean product lines, the company has now started marketing the technology, the manufacturer added.

According to Flamco, the innovation is a sustainable solution for both residential and commercial buildings, and has a lower risk of malfunction.

Explaining the rationale behind the concept, Flamco said that systems that are properly de-aerated, from which both small and larger particulate matter can be removed efficiently, have better output, are quieter and have a longer service life.

The manufacturer lists the following features and advantages:

• Three existing technologies are used simultaneously in the Dual Zone Flow Diversion technology: coalescence, reduction of the flow speed and reduction of pressure. Micro-bubbles adhere to the metal surfaces of the PALL rings in the structure under the influence of coalescence; air bubbles rise to the automatic vent due to the reduction of the flow speed; and gases dissolved in the fluid are released because of reduction in pressure.
• The air and dirt separators prevent three-way valves from sticking, which could lead to a build-up of dirt particles in boilers (heat exchangers), pumps, radiators and pipes. Efficiently separating and removing air bubbles prevents the formation of rust and magnetite in the inner workings of the system. Rust and magnetite can have an adverse effect on the circulation pump.
• Research conducted at the University of Antwerp has shown that the invention removes even microscopic air bubbles from between 10 and 20 μm.
• The optimised through-flow in cooling and heating systems is due to the efficient way in which the Dual Zone Flow Diversion technology separates dirt particles, such as grains of sand, bits of metal and paint or tape residue from the water.
• In common with the air bubbles, lighter dirt particles rise into the special basket with PALL rings, from which they are released via a blow-off cock fitted underneath the automatic vent. Thanks to the low-flow speed, heavier dirt particles drop to the bottom of the separator, where a drain cock is fitted.
• The entire process of separating dirt and air is carried out with minimal loss of pressure.
• The technology makes it possible to use a smaller pump, which consumes less electricity, helping to keep down costs.
• It can be applied to both small and large systems, in sealed heating and cooling systems, and in solar thermal systems in which steam can be created.

Unigulf

Asserting that an aluminium duct system is the best solution for air conditioning transportation systems with pressures up to 1.000 Pa (100 mm of water column) and dimensions of up to 2.500 mm, Unigulf has introduced its P3 Gulf pre-insulated aluminium duct system. The manufacturer claims that the P3 ductal system can be used in any application – ducts installed internally, externally, in aggressive environments or those with strict hygiene requirements. The system is not only based on pre-insulated aluminium panels but is also made of accessories, equipment and know-how customised for the construction and installation of ducts, the manufacturer adds.

Unigulf lists the following product features and advantages:

Energy and eco sustainability:

• Water foaming Hydrotec patent allows ecological expansion without the use of greenhouse effect gasses with GWP = 0 and ODP = 0
• Maximum utilisation of AHU performance
• Increase in efficiency

Thermal insulation:

• High thermal insulation with a thermal conductivity value of λi=0,022 W/(mºC) measured at 10ºC

Air seal:

• Invisible flanging system facilitates elimination of longitudinal leaks and reduction of the ones in the transversal junctions
• Improved air seal class, according to the UNI EN 13403 standard

Fire safety:

• Low fire participation
• Compliance with the principal international safety standards
• Performance to demanding tests (ISO 9705 – Room Corner Test)
• Reduced smoke emissions, low toxicity and opacity of fumes

Sound resistant:

• High acoustic comfort due to efficient linear attenuation, especially at low frequencies
• Vibrations and resonance blocked by insulating panel

Clean air and hygiene:

• Internal aluminium surface eliminates particle release problem
• High level of hygiene guaranteed by aluminium, suitable for food industry
• No contribution from the material to proliferation of bacteria
• Availability of panels with antibacterial treatment

Light:

• Reduced weight compared to sheet metal ducts
• Reduction of load on the bearing structure
• Reduction of bracketing points
• Reduction of labour and time needed for installation

Easy construction:

• Easy transportation
• Quick changes on site possible
• Coded construction procedures

Saying that they are suitable for most commercial and industrial liquid cooling applications, Dolcool has introduced Daw Series air-cooled modular chillers. Available in capacities from 17 KW to 450 KW, they are completely factory-assembled and are ready to operate after being connected to power and water supplies, claims Dolcool.

The manufacturer lists the following product features and advantages:

• The chiller systems include compressors (scroll/screw), operating and safety controls, internal power and control wiring, built-in flow switch and pump On/Off control, and are charged with a refrigerant (R22/R134a) at the factory.
• The unit capacity can be varied by staging the compressors in response to variations in return water temperature.
• A factory-supplied wired remote control centre displays the inlet and outlet water temperature, system status and alarm conditions.
• The fully automatic devices and the remote control centre enable the user to monitor and control the chiller and pumps, the on/off operation and temperature setting, installed as far as 1,000 metres away from the chiller according to the user’s convenience. The operation of the chilled water pump can also be controlled through the remote control centre.
• Each unit is factory-operated and performance-tested at various controlled ambient and water temperature conditions. They are, therefore, engineered to provide trouble-free operation at ambient temperature conditions as high as 55ºC.
• The compact modular design facilitates easy lifting, shifting and erecting, and requires less space.
• The modular construction also helps the user to augment the total chiller capacity by adding attachable modules, if necessary.
• No special foundation work or machine room is required for installation.
• It is simple to operate.
• Automatic operation facilitates increased safety. The unsupervised operation is completely safe, as any abnormal condition automatically initiates shutdown of the related refrigerant circuits.
• Copeland Scroll Compressor and specially designed fans enable a quiet operation. The chiller structure is engineered to minimise the vibration.
• All essential service and maintenance can be performed by easily removable access panel.

Sipos Aktorik

In its newsletter, Sipost, Sipos Aktorik has announced unveiling SIPOS 5 HiMod electric actuator series, which the company says, comes with a High-res Absolute Position encoder with a maximum tolerance of 0.003 %. Sipos claims that by means of the encoder, the HiMod actuator registers the position of the output shaft even when there is a power failure. It adds that as a result, changes of position which could occur, for example, by operating the hand wheel, can be reliably identified, and when power is reinstated, this information is communicated accurately to the control system.

The manufacturer lists the following product features and advantages:

• The continuous precision actuator comes with IP68 Protection Class status, which provides high resistance against corrosion and continuous duty according to Class DEN15714-2.
• The installation procedure is completely non-intrusive and adjustment of end positions can be achieved without opening the actuator.
• The double-sealed electro-connection compartment guarantees that electronic components are kept safe from harmful environmental influences – a feature that is particularly important for actuators during installation.
• It is ideal for situations where continuous high-demand and long-term usage is required.
• Intelligent software solutions are at the heart of the product’s capability, ensuring that they support the most diverse process requirements.
• It comes with a five-year guarantee on motor and gear parts – components that are most subjected to continuous wear-and-tear.
• It works without a battery.

Fundamentals of insulation – critical selection factors is to be a key point of discussion at ASHRAE Oryx Chapter seminar

The ASHRAE-Oryx chapter, in association with M/s FTC Qatar WLL, will be conducting a full-day seminar on two topics –

Fundamentals of insulation – green buildings and Passive fire protection systems. The event will be held on April 30 at The College of North Atlantic (Building 1, Lecture Hall: 1). The presentations will be made on the following topics:

Presenter: George Georgiou, International Sales and Marketing Manager, Sekisui Foam International

Topic: Fundamentals of insulation – critical selection factors and their effect on long-term building sustainability

1. Introduction
2. Insulation – centrepiece of the green building concept and energy savings
   • a) Global perspective (USA, AUS)
   • b) Future trends
3. Fundamentals of insulation – critical factors that affect selection and performance
4. Safety in insulation systems
   • a) A review of current fire and smoke standards and trends
   • b) Deficiencies in current standards
   • c) Third party certification systems
5. Examination of insulation critical performance factors – theory versus reality
   • a) Thermal conductivity
   • b) Vapour permeability
   • c) Water absorption
6. Changes of insulation performance over time and implication to owners
7. Decision-making for insulation – upfront cost versus long- term benefit
   • a) Current trends in decision making
   • b) Lack of awareness of the importance of insulation
   • c) Lack of “long-term” energy-saving perspective
8. Illustration/comparison of energy costs in running AC systems using different types of insulation
   • a) Energy-saving predictor software (Sekisui)

Presenter: Edward Gaynor, Technical Advisor, Promat Fire Protection

Topic: Passive fire protection systems

1. 1. Fire and smoke penetration seals
   • Theory of fire compartmentalisation
   • Failure criteria
   • Penetration seals and fire performance
2. 2. Promat solutions
   • a) Fire rated duct works
   • b) Fire-testing methods
   • c) Design considerations
   • d) Advantages board solutions
   • e) Promat solutions
3. 3. Fire and blast-resistant walls
   • Advantages of demountable barriers
   • Promat solutions for demountable barriers

According to the Chapter, ASHRAE members who wish to attend the event are requested to confirm by e-mail before April 27, after which the registrations will close. For more details, Seenu Pillai of the Chapter is available at +974 5562 6509.

AHRI recently participated in a survey and conference sponsored by the Asia-Pacific Economic Cooperation (APEC) on green buildings and green growth. APEC’s Subcommittee on Standards and Conformance planned and organised the two-part project (survey and conference) to support several energy efficiency, sustainability, and conservation priorities and initiatives established within APEC. AHRI said that its participation focused on the use of specific standards and codes for the use of green building technologies and practices in commercial buildings.

At the conference, results of a survey co-sponsored by AHRI, the Aluminum Association, the International Code Council, and IAPMO were presented.

AHRI discusses direction of HVACR and water heating industry

On March 3, executives from AHRI, ACCA, and HARDI met to discuss the direction of the HVACR and water heating industry, in the US. The meeting is said to have focused on energy legislation and the AHRI consensus agreements, with significant attention paid to enforcement and potentially difficult installations.

The group reportedly had several discussions about tax incentives for HVACR and water heating equipment. They also touched on commercial incentives and the potential of revising section 179D of the Internal Revenue Code (the whole building retrofit tax credit).

ICA reports exhibiting new energy-efficient, smaller diameter copper tube coil designs from Chinese OEMs

The International Copper Association (ICA) has announced that residential air conditioning products are increasingly being fabricated using smaller diameter copper tubes, especially among OEMs based in China. This was evidenced by the fact that coils from five different OEMs – Gree, Haier, Midea, Chigo and HiSense Kelon – were on display at the MicroGroove Technology booth at the China Refrigeration Expo – CR-2011 in Shanghai, with samples representative of both condensers and evaporators for window-type air conditioners as well for split units, the announcement said.

Speaking from ICA’s MicroGroove stall at the expo, ICA’s Deputy Director of Technology Wenson Zheng, said: “The International Copper Association has been cooperating with OEMs on design strategies for increasing the performance of evaporator and condenser coils. The most spectacular gains in heat transfer efficiency have been realised by decreasing the diameter of the copper tubes in these coils.”

He added that most of the coils were taken from actual production models of residential air conditioners, and that research continued on the design and manufacture of coils with even smaller diameter copper tubes.

ICA has listed the coils on display at the exhibition in the attached table, along with the corresponding applications, cooling capacities and OEMs.

The International Copper Association is an organisation for promoting the use of copper worldwide.