Trane SYS-APM001-EN manual Chilled-Water System Variations, Heat Recovery

Page 76

Chilled-Water System Variations

Figure 40. Sidestream plate-and-frame heat exchanger

Chiller 2

 

 

Production

Chiller 1

 

Bypass Line

 

Plate-and-Frame

Distribution

Heat Exchanger

 

70

 

A number of chilled-water system variations can and should be used when appropriate. Each configuration offers specific advantages to solve problems and add value to the system.

Heat Recovery

ASHRAE/IESNA Standard 90.1–200720requires heat recovery in specific applications. Indoor air quality concerns have spurred the use of systems that subcool supply air to dehumidify, then temper, the air to satisfy space conditions. ASHRAE/IESNA Standard 90.1–2007 limits the amount of new reheat energy used in these applications. With these drivers, and energy costs, there has been a resurgence of heat recovery chillers. The example on page 75 describes a cost-effective recovered-heat strategy. This scheme is commonly used for service-water heating in resort hotels and for certain process loads.

A separate application manual21 discusses heat recovery, as does an Engineers Newsletter 22, so it is not discussed in depth in this manual. However, considerations for heat recovery on chilled-water system design are discussed.

Condenser “Free Cooling” or Water Economizer

There are several ways to accomplish free cooling through the use of a water economizer circuit. Three common techniques for chilled water systems are using a plate-and-frame heat exchanger, refrigerant migration, or well, river, or lake water. Each technique is discussed in more detail below and in an Engineers Newsletter 23.

Plate-and-frame heat exchanger

A plate-and-frame heat exchanger may be used in conjunction with a cooling tower to provide cooling during very low wet-bulb temperature conditions. When it is to be used for these purposes, designers often specify a cooling tower larger than necessary for design conditions so that it can be used for many hours with the plate-and-frame heat exchanger.

In this type of water economizer, the water from the cooling tower is kept separate from the chilled-water loop by a plate-and-frame heat exchanger. This is a popular configuration because it can achieve high heat-transfer efficiency without cross-contamination. With the addition of a second condenser-water pump and proper piping modifications, this heat exchanger can operate simultaneously with the chiller, provided the chiller is placed downstream of the heat exchanger (as shown in Figure 40). As much heat as possible is rejected through the heat exchanger while the chiller handles the rest of the cooling

Chiller System Design and Control

SYS-APM001-EN

Page 75 Page 77
Image 76
Page 75 Page 77
Contents May Page Chiller System Design and Control Preface Contents 100 Primary System Components ChillerPrimary System Components Chiller evaporatorEffect of chilled-water temperature Effect of chilled-water flow rate and variationWater-cooled condenser Effect of condenser-water temperatureEffect of condenser-water flow rate Maintenance Air-cooled condenserAir-cooled versus water-cooled condensers Packaged or Split System?Low-ambient operation Energy efficiencyLoads Air-cooled or water-cooled efficiencyThree-way valve load control Two-way valve load controlVariable-speed pump load control Face-and-bypass dampersChilled-Water Distribution System Chilled-water pumpPump per chiller Distribution pipingManifolded pumps Pumping arrangements Constant flow systemCondenser-Water System Cooling towerPrimary-secondary system Variable-primary systemCondenser-water pumping arrangements Effect of load on cooling tower performanceEffect of ambient conditions on cooling tower performance Single tower per chillerChiller control Unit-Level ControlsRecommended chiller-monitoring points per Ashrae Standard Centrifugal chiller capacity control Centrifugal chiller with AFDAFD on both chillers Application Considerations Small Chilled-Water Systems 1-2 chillersVariable flow Application Considerations Constant flowCondensing method Application Considerations Number of chillersParallel or series Part load system operationManaging control complexity Mid-Sized Chilled-Water Systems ChillersPreferential vs. equalized loading and run-time Large chilled-water system schematic Large Chilled-Water Systems + Chillers, District CoolingPipe size PowerWater Chiller performance testing Limitations of field performance testingChiller Plant System Performance ControlsSYS-APM001-EN SYS-APM001-EN System Design Options Guidance for Chilled- and Condenser-Water Flow RatesStandard rating temperatures Chilled-Water TemperaturesSystem Design Options Chilled- and Condenser-Water Flow Rates Condenser-Water TemperaturesStandard rating flow conditions System Design Options Selecting flow rates DP2/DP1 = Flow2/Flow11.85 Low-flow conditions for cooling tower Base Case Low FlowTotal system power Component Power kW Base Case Low Flow System summary at full loadCoil response to decreased entering water temperature Chilled water system performance at part loadEntering fluid temperature, F C Cooling-tower options with low flowSmaller tower System designΔT2 = 99.1 78 = 21.1F or 37.3 25.6 = 11.7C Same tower, smaller approachSame tower, larger chiller Same tower, smaller approach Present Smaller ApproachRetrofit opportunities Retrofit capacity changes Larger Present Chiller Same towerCost Implications Misconceptions about Low-Flow Rates Misconception 1-Low flow is only good for long piping runsKWh SYS-APM001-EN System Configurations Parallel ChillersSystem Configurations Parallel chillers with separate, dedicated chiller pumpsSeries Chillers Series chillersPrimary-Secondary Decoupled Systems Hydraulic decouplingCheck valves System Configurations Production Production loopSystem Configurations Distribution Distribution-loop benefits of decoupled system arrangementCampus CommonTertiary or distributed Decoupled system-principle of operation Tertiary pumping arrangementFlow-based control Temperature-sensingFlow-sensing Adding a chiller Multiple chilled-water plants on a distribution loopSubtracting a chiller Pump control in a double-ended decoupled system Double-ended decoupled systemChiller sequencing in a double-ended decoupled system Variable-Primary-Flow Systems Other plant designsAdvantages of variable primary flow Operational savings of VPF designsChiller selection requirements Dispelling a common misconceptionFlow, ft.water Flow rate Managing transient water flows Flow-rate changes that result from isolation-valve operationSystem Configurations System design and control requirements Effect of dissimilar evaporator pressure dropsAccurate flow measurement Chiller sequencing in VPF systems Bypass flow controlAdding a chiller in a VPF system Flow-rate-fluctuation examplesSubtracting a chiller in a VPF system Sequencing based on loadOther VPF control considerations Select slow-acting valves to control the airside coilsPlant configuration Consider a series arrangement for small VPF applicationsGuidelines for a successful VPF system Chiller selectionPlant configuration Bypass flowChiller sequencing Airside controlHeat Recovery Chilled-Water System VariationsCondenser Free Cooling or Water Economizer Plate-and-frame heat exchangerChilled-Water System Variations Refrigerant migrationRefrigerant migration chiller in free-cooling mode Well, river, or lake waterPreferential Loading Preferential loading parallel arrangementPreferential loading sidestream arrangement Sidestream plate-and-frame heat exchangerSidestream with alternative fuels or absorption Chilled-Water System VariationsPreferential loading series arrangement Sidestream system controlSeries-Counterflow Application Series-series counterflowEvaporators Unequal Chiller SizingCondensers Low ΔT Syndrome System Issues and ChallengesAmount of Fluid in the Loop System Issues and Challenges Chiller response to changing conditionsSystem response to changing conditions ExampleMinimum capacity required ContingencyType and size of chiller System Issues and Challenges Location of equipment Alternative Energy SourcesWater and electrical connections Ancillary equipmentAlternative fuel Plant ExpansionThermal storage Applications Outside the Chiller’s Range Retrofit OpportunitiesFlow rate out of range System Issues and Challenges Temperatures out of range Precise temperature controlPrecise temperature control, multiple chillers Chilled water reset-raising and lowering System ControlsChilled-Water System Control Chilled-water pump controlSystem Controls Critical valve reset pump pressure optimizationNumber of chillers to operate Condenser-Water System Control Minimum refrigerant pressure differentialVFDs and centrifugal chillers performance at 90% load Chillers DifferenceCondenser-water temperature control Cooling-tower-fan controlChiller-tower energy balance Chiller-tower energy consumptionSystem Controls Variable condenser water flow Chiller-tower-pump balanceDecoupled condenser-water system Effect of chiller load on water pumps and cooling tower fansCDWP-2 Failure Recovery Failure recoveryConclusion Glossary Glossary Pumps systemGlossary References Plant. Idea 88th Annual Conference Proceedings 1997References Engineering July102 Index AshraeIndex 105 106 Page Trane

SYS-APM001-EN specifications

The Trane SYS-APM001-EN is an advanced control system designed for HVAC (Heating, Ventilation, and Air Conditioning) applications, specifically tailored to enhance energy efficiency and system performance. This comprehensive solution integrates cutting-edge technologies to optimize climate control in commercial and industrial environments.

One of the main features of the SYS-APM001-EN is its intuitive user interface. The system is equipped with a large, easy-to-read display that provides real-time data on system performance, energy usage, and environmental conditions. This user-friendly interface makes it simple for operators to monitor and adjust settings, ensuring optimal comfort levels and efficient energy consumption.

Another key characteristic of the SYS-APM001-EN is its advanced data analytics capabilities. The system collects and analyzes data from various sensors throughout the building, providing insights into occupancy patterns, equipment performance, and energy consumption trends. This data-driven approach allows facility managers to make informed decisions about system adjustments, predictive maintenance, and energy savings.

The SYS-APM001-EN also boasts robust integration capabilities. It can seamlessly connect with a variety of building management systems (BMS) and other third-party devices. This interoperability enables a cohesive operational ecosystem where HVAC systems can communicate and cooperate with lighting, security, and fire safety systems, enhancing overall building efficiency.

Energy efficiency is a hallmark of the SYS-APM001-EN, as it implements sophisticated algorithms to optimize system operation. These algorithms adjust equipment performance in real-time based on current conditions, thereby reducing energy waste and lowering operational costs. The system is designed to support multiple energy-saving strategies, including demand-controlled ventilation and optimal start/stop scheduling.

Additionally, the SYS-APM001-EN is built with scalability in mind, accommodating facilities of various sizes and configurations. Whether it’s a small office building or a large industrial complex, the system can be tailored to meet specific needs, ensuring that HVAC performance aligns with operational goals.

In conclusion, the Trane SYS-APM001-EN is an innovative HVAC control solution that emphasizes user experience, data-driven decision-making, and energy efficiency. With its advanced features and technologies, it is an essential tool for optimizing building performance and enhancing occupant comfort while reducing environmental impact.
Top Page Image Contents