ASHRAE Journal - December 2009 - 46

Containerized Water Chilling Plant Energy Savings This type of plant is often used for getting cold water in the range of 1°C to 2°C (34°F to 36°F). R-22/R-134a generally is used. A containerized water chilling plant includes: • First and second circuits consist of reciprocating or screw compressors; • Evaporative condenser with two coil sections; • Direct expansion type plate heat exchanger (PHE) for first stage; • Direct expansion type PHE for second stage; • Direct expansion plate type chilled water tank; and • Primary water pump. All of this equipment is installed inside a container and connected. The first refrigeration circuit is used for cooling the water from 38°C to 14°C (100°F to 57°F). The evaporation temperature is kept at 10°C (50°F) in the first circuit. The compressor, evaporative condenser, and direct expansion type PHE (Stage 1) are part of the first refrigeration circuit. The second refrigeration circuit is used for cooling water from 14°C to 1°C (57°F to 34°F) in direct expansion type PHE (Stage 2) and later in the chilled water tank. A pressure regulating control valve helps maintain evaporation temperature at 1°C (34°F), helping to avoid freezing in the PHE. A –5°C (23°F) evaporation temperature is maintained in the chilled water tank for cooling the water up to 1°C (34°F). The evaporative condenser has two independent coils, which are used for condensing the refrigerant in the first and second circuits. The evaporative condenser has a common fan and recirculation cooling water pump for spraying water over the coils. A containerized plant requires less space than a conventional plant, but it is difficult to place all the equipment inside a container. The general arrangement of PHEs, compressor and chilled water tank should not hinder the overall movement of maintenance engineers and technicians. The plant’s equipment layout should be finalized after generating various 3-D piping models. The pipes are supported from the roof of the container so that a maintenance person can easily move inside the container. The evaporative condenser has two coil sections (independent two compressor circuits), which provide flexibility in running any compressor circuit. Let’s examine the power requirement of a conventional plant versus a containerized water chilling plant. Design Conditions The total power requirement for a conventional plant is higher than a containerized water chilling plant: 171.2 kW (conventional plant using R-22) minus 140 kW (containerized plant using R-22) equals 31.2 kW. Assuming a rate of $0.10/kWh, this difference is $27,331.20 in average annual savings. Note: A containerized plant with R-134a uses a comparable amount of power to a containerized plant with R-22 (135.5 kW versus 140 kW). Containerized Water Chilling Plant Advantages Advantages of containerized water chilling plant for concrete cooling include: • Compact design. • No site activity is involved. Only water and electric power are needed. • Container can be relocated to any site easily. • Hot and cold water tanks are eliminated. • No foundation is required. • The refrigerant charge is less than for a conventional plant because of the direct expansion chillers. • Refrigeration is divided into two circuits. The COP of the combined cycle is 3.18 with R-22 and 3.27 with R-134a. • Requires only primary pump for flow. • No cooling tower is required. Cooling water piping connecting condenser, cooling tower and pump are eliminated. • Typically, a 2.94 L/s (6.24 cfm) plant that cools water from 35°C to 1°C (95°F to 34°F) requires a connected electrical load of 140 kW with R-22 and 135.5 kW with R-134a. Summary • • • • • Makeup Water Temperature = 35°C (95°F) Chilled Water Temperature = 1°C (34°F) Condensing Temperature = 43°C (109°F) Wet-Bulb Temperature = 30°C (86°F) Water Flow Requirement = 2.94 L/s (6.24 cfm) It is evident that a containerized water chilling plant for concrete cooling is a better option compared to a conventional water chilling plant for concrete cooling. A containerized water chilling plant requires less electrical power than a conventional water chilling plant. A containerized water chilling plant has other advantages as well, it is compact, easy to install on site, no foundation is needed, it can be transported with no delays in deliveries, and it requires less refrigerant charge. The initial cost of a containerized plant is more than a conventional plant, but the cost is easily compensated by the advantages and operating cost. References 1. ACI. 2007. “305.1-06: Specification for Hot Weather Concreting.” Farmington Hills, Mich.: American Concrete Institute. 2. Naik, T.R. 1985. Temperature Effects on Concrete, pp. 88–106. Philadelphia: ASTM International. 3. PCA. 2009. “Cement and Concrete Basics.” www.cement.org/ basics. Skokie, Ill.: Portland Cement Association. 4. ACI. 2000. “305R-1999: Hot Weather Concreting.” Farmington Hills, Mich.: American Concrete Institute. ashrae.org December 2009 Chilling Circuit • Stage 1: 35°C to 13°C in First PHE (95°F to 55°F) • Stage 2: 13°C to 4°C in Second PHE (55°F to 39°F) • Stage 3: 4°C to 1°C in Water Chilling Tank (39°F to 34°F) 46 ASHRAE Journal

ASHRAE Journal - December 2009

Table of Contents for the Digital Edition of ASHRAE Journal - December 2009

ASHRAE Journal - December 2009
Contents
Commentary
Industry News
Letters
Meetings and Shows
ASHRAE Building EQ Program
Feature Articles
A Closer Look at Chiller Ratings
Cooling With Less Air: Using Underfloor Air Distribution and Chilled Beams
Cooling Concrete: Containerized Water Chilling Plant
Geothermal for Community Center
Anniversary Feature: Air-Recovery System Versus Conventional Air Conditioning
Technical Topics
New Product Preview
Products
Emerging Technologies
Washington Report
People
Special Products
2009 Feature Articles Indices
Classified Advertising
Advertisers Index
ASHRAE Journal - December 2009 - ASHRAE Journal - December 2009
ASHRAE Journal - December 2009 - Cover2
ASHRAE Journal - December 2009 - 1
ASHRAE Journal - December 2009 - 2
ASHRAE Journal - December 2009 - Contents
ASHRAE Journal - December 2009 - 4
ASHRAE Journal - December 2009 - Commentary
ASHRAE Journal - December 2009 - Industry News
ASHRAE Journal - December 2009 - 7
ASHRAE Journal - December 2009 - 8
ASHRAE Journal - December 2009 - 9
ASHRAE Journal - December 2009 - 10
ASHRAE Journal - December 2009 - Letters
ASHRAE Journal - December 2009 - 12
ASHRAE Journal - December 2009 - 13
ASHRAE Journal - December 2009 - 14
ASHRAE Journal - December 2009 - 15
ASHRAE Journal - December 2009 - Meetings and Shows
ASHRAE Journal - December 2009 - 17
ASHRAE Journal - December 2009 - Feature Articles
ASHRAE Journal - December 2009 - 19
ASHRAE Journal - December 2009 - 20
ASHRAE Journal - December 2009 - 21
ASHRAE Journal - December 2009 - A Closer Look at Chiller Ratings
ASHRAE Journal - December 2009 - 23
ASHRAE Journal - December 2009 - 24
ASHRAE Journal - December 2009 - 25
ASHRAE Journal - December 2009 - 26
ASHRAE Journal - December 2009 - 27
ASHRAE Journal - December 2009 - 28
ASHRAE Journal - December 2009 - 29
ASHRAE Journal - December 2009 - 30
ASHRAE Journal - December 2009 - 31
ASHRAE Journal - December 2009 - 32
ASHRAE Journal - December 2009 - 33
ASHRAE Journal - December 2009 - Cooling With Less Air: Using Underfloor Air Distribution and Chilled Beams
ASHRAE Journal - December 2009 - 35
ASHRAE Journal - December 2009 - 36
ASHRAE Journal - December 2009 - 37
ASHRAE Journal - December 2009 - 38
ASHRAE Journal - December 2009 - 39
ASHRAE Journal - December 2009 - 40
ASHRAE Journal - December 2009 - 41
ASHRAE Journal - December 2009 - Cooling Concrete: Containerized Water Chilling Plant
ASHRAE Journal - December 2009 - 43
ASHRAE Journal - December 2009 - 44
ASHRAE Journal - December 2009 - 45
ASHRAE Journal - December 2009 - 46
ASHRAE Journal - December 2009 - 47
ASHRAE Journal - December 2009 - Geothermal for Community Center
ASHRAE Journal - December 2009 - 49
ASHRAE Journal - December 2009 - 50
ASHRAE Journal - December 2009 - 51
ASHRAE Journal - December 2009 - Anniversary Feature: Air-Recovery System Versus Conventional Air Conditioning
ASHRAE Journal - December 2009 - 53
ASHRAE Journal - December 2009 - 54
ASHRAE Journal - December 2009 - 55
ASHRAE Journal - December 2009 - 56
ASHRAE Journal - December 2009 - 57
ASHRAE Journal - December 2009 - 58
ASHRAE Journal - December 2009 - 59
ASHRAE Journal - December 2009 - 60
ASHRAE Journal - December 2009 - 61
ASHRAE Journal - December 2009 - Technical Topics
ASHRAE Journal - December 2009 - 63
ASHRAE Journal - December 2009 - 64
ASHRAE Journal - December 2009 - New Product Preview
ASHRAE Journal - December 2009 - 66
ASHRAE Journal - December 2009 - 67
ASHRAE Journal - December 2009 - 68
ASHRAE Journal - December 2009 - 69
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ASHRAE Journal - December 2009 - 112
ASHRAE Journal - December 2009 - 113
ASHRAE Journal - December 2009 - Products
ASHRAE Journal - December 2009 - 115
ASHRAE Journal - December 2009 - 116
ASHRAE Journal - December 2009 - Emerging Technologies
ASHRAE Journal - December 2009 - Washington Report
ASHRAE Journal - December 2009 - 119
ASHRAE Journal - December 2009 - People
ASHRAE Journal - December 2009 - Special Products
ASHRAE Journal - December 2009 - 2009 Feature Articles Indices
ASHRAE Journal - December 2009 - 123
ASHRAE Journal - December 2009 - 124
ASHRAE Journal - December 2009 - 125
ASHRAE Journal - December 2009 - Classified Advertising
ASHRAE Journal - December 2009 - 127
ASHRAE Journal - December 2009 - Advertisers Index
ASHRAE Journal - December 2009 - Cover3
ASHRAE Journal - December 2009 - Cover4
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