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The chilled water system, equipment, and components will be designed in accordance with the applicable industry standards and shall conform to the provisions of the latest issue of applicable U.S.A. codes and standards including but not limited to the following:

• Uniform Building Code (UBC)

• Uniform Mechanical Code

• National Fire Protection Agency Codes and Standards (NFPA) or local equivalent

• American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE)

• American Society of Mechanical Engineers (ASME)

• American Society for Testing and Materials (ASTM)

• American National Standards Institute/Hydraulic Institute (ANSI/HI) Pump Standards

• Applicable Local Codes and Standards

Q06024-IDCP-RPT-ME-001-REV 3 5-4 Stanley Consultants

General

The Integrated District Cooling Plant at The Pearl Project includes a new central chilled water plant to serve the cooling needs for the proposed building construction on the island. The new development consists of several high-rise buildings and villas, which will use the chilled water from the IDCP to serve their air-conditioning needs. Each building will include an energy transfer station and/or heat exchanger as the “point of use” for chilled water.

The IDCP is an independent chilled water plant designed for an ultimate capacity of 120,000 tons and an initial capacity of 115,000 tons. The size and number of the chillers were selected based upon the Alternate 2 Bid proposed by CAT and accepted by Qatar Cool prior to award of the contract. These discussions resulted in the decision to use 2,500-ton nominal electric motor-driven centrifugal chillers arranged in pairs using a series-series, counter-flow configuration. To achieve the initial capacity, the plant will include 23 chiller pairs arranged as shown on Drawings (Q06024-IDCP-A-101). Provisions will be incorporated into the design of the IDCP for the future expansion of the plant to its ultimate capacity using one additional chiller pair. The main equipment and auxiliaries for the IDCP include:

• Chillers – Arranged in pairs using a series-series, counter-flow configuration.

• Cooling Towers.

• Chilled Water Distribution Pumps (Constant Speed).

• Condenser Water Pumps (Constant Speed).

• Refrigerant Transfer Unit with Pump-Out Receiver.

• Reverse Osmosis (R.O.) Equipment (i.e. Salt Water R.O. Units, Brackish Water R.O. Units, Sand Filters, Pumps, and Tanks).

• Continuous Condenser Water Filtration Equipment.

• Water Treatment System.

• Cooling Tower Blowdown System.

• Electrical Switchgear, Transformers, etc. (see Section 6).

• Plant Control System (see Section 7).

Chillers

Forty-six (23 pairs) 2,500-ton nominal electric motor-driven centrifugal chillers will be installed as a part of this project. Chiller pairs will be rated in accordance with ARI 550/590 based upon the specified ARI and zero tolerance performance. In addition, the chillers will operate without loss of capacity at ambient temperatures as high as 104°F. Each chiller will be factory assembled and tested and located as shown on the Drawings (Q06024-IDCP-A- 101). The chillers will be designed to cool 7,500 gpm (1.5 gpm per ton) of chilled water from 56°F to 40°F and reject that heat to 11,000 gpm (2.2 gpm per ton) of condenser water. The design water temperature rise across the condenser will be from 92°F to 105°F.

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The chiller compressor will not exceed a sound pressure level of 85 dBA at a distance of 3 feet from the compressor, condenser, and evaporator during full load operation. This sound pressure level is based upon a reference pressure of 20 micro-pascals.

In addition, the chillers will be used in a direct-primary (constant speed) pumping scheme consisting of pumps that are operated in conjunction with the chillers. This will allow the system to vary the total flow to match the load of the distribution system, but maintain a constant flow through the chiller evaporator. Refer to Section 7 for Control Systems Design Statement.

The refrigeration cycle will utilize R-134a or R-123 as its refrigerant and the chiller components and auxiliaries are as follows:

• Refrigerant Condenser

• Refrigerant Evaporator

• Economizer (As Required)

• Compressor

• Couplings

• Compressor Motors

• Auxiliary Motors

• Purge System (R-123 Only)

• Vacuum Prevention System (R-123 Only)

• Compressor Motor Starters

• Auxiliary Motor Starters

• Control System

• Accessories and Associated Piping

• Structural Steel Base with Seismic Restraints and Vibration Isolation Devices

The condensers and evaporators will be of horizontal, shell and tube design in a single-pass configuration. The design will be stamped in accordance with ASME Section VIII.

Shell, tube sheets and supports will be constructed of carbon steel and the tubes of seamless copper. Tubes will be 3/4-inch OD enhanced bore with integral fins and have a maximum fouling factor of 0.00025. In addition, the evaporator and condenser pressure drop will not exceed 15 feet of head loss.

Each chiller condenser will include a tube brush cleaning system that will scour the tubes clean by reversing the flow through the condenser using automatic control valves as shown in the piping configuration on the Drawings (Q06024-IDCP-M-I-614).

The water boxes will be of welded, non-marine carbon steel construction with mechanical coupling grooves suitable for welding or bolted clamp-type coupling. Refrigerant side relief

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valves will be provided and designed in accordance with ANSI B9.1/ASHRAE 15 safety code.

A refrigerant sub-cooler or flash-type economizer will be provided with the chillers, at manufacturer’s option, to improve cycle efficiency.

The compressor will be open or hermetic drive, horizontally-split centrifugal-type, and driven by an electric motor. Open drive motors will be totally enclosed, water cooled (TEWAC) type using condenser water at a temperature of 92°F.

The chiller will be guaranteed to provide 100 percent of rated capacity for any given pair of chillers, while not exceeding 0.748 kW per ton of electrical usage. Performance testing will be conducted in accordance with the latest edition of ARI 550/590.

Cooling Towers

Two, 12-cell, 60,000-ton cooling tower cells will be installed as a part of this project. Condenser water leaving the chillers enters the tower through the distribution header and is discharged through nozzles. The water falls through the fill, while air is drawn up to the fan stack in a counter-flow fashion. Heat is rejected to the air through an evaporative cooling process. Air is drawn through each cooling tower at a design inlet wet bulb temperature of 87°F to provide the required evaporative cooling.

The cooling tower cells will be located on the roof of the plant and designed as an integral architectural element of the facility. Exterior treatments will blend with the overall architectural theme of the plant.

The tower components include:

• Fan

• Motor (Variable Speed)

• Fill

• PVC Drift Eliminators

• Distribution Piping and Nozzles

• Concrete Basin and Fiberglass Walls

• Internal Support System

• Chemical Water Treatment System

The cooling towers will be designed for wind loading in accordance with the 1997 UBC for 90 miles per hour wind and an exposure D. In addition, the cooling towers will be designed in accordance with the 1997 UBC for a Seismic Zone 2A.

The tower cells will be constructed of double wall, FRP using structural shapes of pultruded fiberglass components having a flame spread rating of less than 25. The tower basin will be elevated above the roof level to allow for adequate clearance for the condenser water pumps and will be constructed of concrete.

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Each cooling tower cell will be divided into three basins at the building control joint locations. These basins will be connected through equalization lines that will be designed to maintain a maximum differential in water levels of 1 inch.

The fans will be multi-blade propeller type constructed of fiberglass blades and an epoxy coated, galvanized steel hub. The fan will be electric motor-driven through reduction gears and a variable frequency drive (VFD). The fan motors will be totally enclosed, fan-cooled (TEFC) type and located outside of the air stream. The variable speed drive allows for load- following at the tower as well as reduction in ambient noise during off-peak cooling hours. The heat transfer medium will be cross-corrugated polyvinyl chloride (PVC). In addition, the cooling towers will include multi-pass, wave form drift eliminators constructed of PVC and capable of reducing the cooling tower drift to 0.0005 percent of the condenser water flow rate.

The cooling tower distribution system and nozzles will provide an even distribution of water over the fill and be capable of allowing flow reductions down to 50 percent of design flow without modifications or adjustments. In addition, the pressure drop across a nozzle will not exceed 2 psid.

The cooling towers will be guaranteed to provide 100 percent of rated capacity at the design conditions listed above. Performance testing will be conducted by an independent impartial third party in accordance with the latest edition of CTI Publication ATC-105.

Cooling towers shall not exceed sound pressure level of 50 dBA at 50 meters perpendicular from tower wall between hours of 8:00 p.m. to 8:00 a.m. by any single cooling tower cell. The sound pressure levels are in decibels (dB) relative to standard reference pressure of 0.0002 Dynes/sq. cm. Distances listed are from the bottom edge of air inlets facing outward from the plant. Performance testing will be conducted by an independent impartial third party in accordance with the latest edition of CTI Code ATC-128.

Make-up water and chemical treatment for the cooling tower water will be added at the basin of each tower and controlled on a tower-by-tower basis. The chemical injection system will be designed to allow for even distribution of chemicals within the basin. In addition, three side stream centrifugal filter separators will be provided for each 12-cell tower for removal of suspended solids. The side stream filtration system will be based upon a flow rate equal to 10 percent of the total condenser water flow rate. The condenser water will have the following minimum characteristics:

• pH Range: 8.0 to 9.0.

• Chlorides (NaCl): <200 ppm.

• Sulfate (SO4): <100 ppm.

• Sodium Bicarbonate (NaHCO3): Negligible.

• Calcium (CACO3): <50 ppm.

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• Silica (SiO2): Negligible.

• Maximum Water Temperature: 110ºF.

Cooling tower blowdown will be based upon two to six cycles of concentration depending upon the operating scenario. The sanitary system will be sized accordingly.

Chilled Water Pumping Scheme

The chilled water pumping scheme will be of direct primary design with constant speed distribution pumps. It consists of a single, variable volume chilled water loop, which combines the chilled water plant and distribution systems. In order to vary chilled water flow to match cooling load (position of two-way control valves), this pumping scheme allows the flow from the plant to adapt to varying distribution conditions instead of having an independent secondary loop. The chilled water pumps perform double duty by both circulating chilled water through the chillers as well as the piping network. The flow is varied by adjusting the quantity of chillers/pumps that are in operation.

Each chilled water distribution pump serves a dedicated chiller pair and will be sized for 7,500 gpm (16°F ∆T), 330 feet of head (estimated), and a maximum motor power of 900 Hp. The pumps will be motor-driven centrifugal, horizontal split case type with double suction and single stage features. The casing will be cast or ductile iron as required for the maximum working pressure. The impeller will be constructed of bronze, fully enclosed, and dynamically balanced. The pumps will include single, cartridge-type mechanical seals, each with an API Plan 11 mechanical seal flushing system. Pump motors will be in accordance with IP 54 and non-overloading throughout the entire pump curve. The pump efficiency will not be less than 85 percent.

Condenser Water Pumping Scheme

Condenser water pumps will be installed in a headered arrangement to allow any cooling tower cell to serve any chiller on a given condenser water system. These pumps will be located on the roof at each cooling tower cell and the pump discharges connected in the headered arrangement. The condenser water piping enters the IDCP through two pipe shafts located in the center of the roof, as shown on the Drawings (Q06024-IDCP-MP-104).

Each condenser water pump serves a dedicated cooling tower and will be sized for 11,000 gpm (13°F ∆T), 115 feet of head (estimated), and a maximum motor power of 400 Hp.

The pumps will be motor-driven centrifugal, vertical turbine type. The discharge head assembly will be constructed of high grade cast iron or fabricated steel and include an ANSI Class 150 discharge flange. The impeller will be constructed of silicon bronze, enclosed or semi-open, and dynamically balanced. Pump motors will be in accordance with IP 54 and non-overloading throughout the entire pump curve. The pump efficiency will not be less than 80 percent.

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Piping System

As previously stated, the chilled water piping system will be arranged in a direct primary fashion. The chilled water and condenser water pipe sizing will, in general, be based upon the following criteria:

• Maximum design velocity of 15 feet per second.

• Maximum head loss of 2.0 feet per 100 feet of pipe.

The piping will be constructed of carbon steel, designed in accordance with the requirements of ASME B31.1 and shall have a minimum thickness of standard weight pipe, but wall thickness will be sufficient for the pressure class of the system.

The major chilled water piping headers will be 48-inch diameter and will be located within trenches. This maintains a “clean” operating floor and simplifies normal operation and maintenance functions within the plant. The major condenser water headers will be 60-inch diameter and are located above the center access aisle. These headers will be supported from structural steel below that is directly connected to the columns. See Drawing Q06024-IDCP- MP-100.

The chilled water system is divided into two hydraulically independent loops, each of which serves the looped network piping system. Two separate pairs of chilled water headers leave the IDCP and connect independently into the network piping. Each of the two headered systems will include a bypass line between the supply and return headers with a self- contained, back-pressure regulating valve. The purpose of this valve is to protect the chilled water system from over pressurization.

Manual isolation within the system will typically be through the use of butterfly valves in accordance with Section 60, Paragraph 7.2.5. Wafer-style check valves will be included at the discharge of each pump. All valves will be rated in accordance with the system design pressure and temperature.

Pipe supports for the IDCP will be in accordance with Section 60, Part 8 of the Tender Specifications as well as the applicable MSS Standards.

Chemical Treatment System

The chemical treatment system shall include corrosion coupons, conductivity sensors, make- up water system and metering, chemical storage, piping, and injection equipment.

The chilled water system will be treated for protection against corrosion as a primary consideration and microbiological growth as a secondary consideration. Corrosion within the chilled water system will be controlled at 2 mpy maximum. Chemicals will be injected into the system using suitable sized, skid-mounted dosing pumps.

The condenser water system will be treated for protection against deposition, corrosion, and microbiological growth. Corrosion within the condenser water system will be controlled at 3 mpy. Microbiological growth will be controlled using biocide and effective bio-dispersant, as required, to operate at pH above 8.0.

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Condenser water chemical treatment system shall include conductivity controlled bleed down, level controls, dosing pumps for bio-dispersant and chlorine donor, chemical storage tanks, and controls. Chemicals will be injected into the system using suitable sized, skid- mounted dosing pumps.

Miscellaneous

In addition to the main equipment and piping, the process is supported by several auxiliary systems:

• A mobile refrigerant transfer unit with pump-out receiver sized for the refrigerant charge of one chiller when the tank is 80 percent filled with refrigerant at 122°F.

• Chilled water expansion tanks will be provided on the system to allow for the thermal expansion and contraction of the water. The pressure at the expansion tanks will be set based upon maintaining a minimum of 4 psig at the highest elevation within the system.

• Chilled water make-up will be provided from the site potable water service and connected to the system at the expansion tank location.

• Cooling tower make-up water will be provided from a combination of three sources: - Site Potable Water: 5,000 cubic meters per day (920 gpm).