Trane SYS-APM001-EN System Design Options, Guidance for Chilled- and Condenser-Water Flow Rates

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System Design Options

For more information, refer to ARI Standard 550/590-2003, Performance Rating of Water Chilling Packages Using the Vapor Compression Cycle and the ARI Standard 560-2000, Absorption Water Chiller and Water Heating Packages. Both are published by the Air- Conditioning, Heating, and Refrigeration Institute. www.ahrinet.org

There are many chilled-water-system design options; however, in a basic sense, each option is a function of flow, temperature, system configuration, and control. This section discusses the effect of flow rate and temperature decisions.

It is important to remember that temperatures and flow rates are variables. By judicious selection of these variables, chilled-water systems can be designed to both satisfy chilled-water requirements and operate cost effectively.

Chilled-water systems are often designed using flow rates and temperatures applied in testing standards developed by the Air-Conditioning, Heating, and Refrigeration Institute (AHRI), ARI 550/590–2003 for vapor compression chillers and ARI 560–2000 for absorption chillers (see sidebar). These benchmarks provide requirements for testing and rating chillers under multiple rating conditions. They are not intended to prescribe the proper or optimal flow rates or temperature differentials for any particular system. In fact, as component efficiency and customer requirements change, these standard rating conditions are seldom the optimal conditions for a real system, and industry guidance recommends lower flow rates with resultant higher temperature differences. There is great latitude in selecting flow rates, temperatures, and temperature differences.

Selecting Chilled- and Condenser-Water Temperatures and Flow Rates

Leaving chilled-water and entering condenser-water temperature selection can be considered independently of their respective flow rates. However, temperatures and flow rates should be selected together to design an efficient and flexible chilled-water system.

Guidance for Chilled- and Condenser-Water Flow Rates

The ASHRAE GreenGuide 8 (pp 146-147) states:

In recent years, the 60% increase in required minimum chiller efficiency from 3.80 COP (ASHRAE Standard 90-75) to 6.1 COP (ASHRAE Standard 90.1-2004) has led to reexamination of the assumptions used in designing hydronic media flow paths and in selecting movers (pumps) with an eye to reducing energy consumption… Simply stated, increase the temperature difference in the chilled water system to reduce the chilled-water pump flow rate…

The CoolTools™ Chilled Water Plant Design Guide recommends starting with a chilled-water temperature difference of 12°F to 20°F [7°C to 11°C], and it

SYS-APM001-EN

Chiller System Design and Control

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Contents May Page Chiller System Design and Control Preface Contents 100 Chiller Primary System ComponentsChiller evaporator Primary System ComponentsEffect of chilled-water flow rate and variation Effect of chilled-water temperatureEffect of condenser-water temperature Water-cooled condenserEffect of condenser-water flow rate Air-cooled condenser MaintenanceAir-cooled versus water-cooled condensers Packaged or Split System?Energy efficiency Low-ambient operationAir-cooled or water-cooled efficiency LoadsTwo-way valve load control Three-way valve load controlFace-and-bypass dampers Variable-speed pump load controlChilled-water pump Chilled-Water Distribution SystemDistribution piping Pump per chillerManifolded pumps Constant flow system Pumping arrangementsCooling tower Condenser-Water SystemPrimary-secondary system Variable-primary systemEffect of load on cooling tower performance Condenser-water pumping arrangementsEffect of ambient conditions on cooling tower performance Single tower per chillerUnit-Level Controls Chiller controlRecommended chiller-monitoring points per Ashrae Standard Centrifugal chiller with AFD Centrifugal chiller capacity controlAFD on both chillers Small Chilled-Water Systems 1-2 chillers Application ConsiderationsApplication Considerations Constant flow Variable flowCondensing method Number of chillers Application ConsiderationsParallel or series Part load system operationMid-Sized Chilled-Water Systems Chillers Managing control complexityPreferential vs. equalized loading and run-time Large Chilled-Water Systems + Chillers, District Cooling Large chilled-water system schematicPower Pipe sizeWater Limitations of field performance testing Chiller performance testingChiller Plant System Performance ControlsSYS-APM001-EN SYS-APM001-EN Guidance for Chilled- and Condenser-Water Flow Rates System Design OptionsChilled-Water Temperatures Standard rating temperaturesSystem Design Options Condenser-Water Temperatures Chilled- and Condenser-Water Flow RatesStandard rating flow conditions System Design Options Selecting flow rates Low-flow conditions for cooling tower Base Case Low Flow DP2/DP1 = Flow2/Flow11.85System summary at full load Total system power Component Power kW Base Case Low FlowChilled water system performance at part load Coil response to decreased entering water temperatureCooling-tower options with low flow Entering fluid temperature, F CSmaller tower System designSame tower, smaller approach ΔT2 = 99.1 78 = 21.1F or 37.3 25.6 = 11.7CSame tower, smaller approach Present Smaller Approach Same tower, larger chillerRetrofit capacity changes Larger Present Chiller Same tower Retrofit opportunitiesCost Implications Misconception 1-Low flow is only good for long piping runs Misconceptions about Low-Flow RatesKWh SYS-APM001-EN Parallel Chillers System ConfigurationsParallel chillers with separate, dedicated chiller pumps System ConfigurationsSeries chillers Series ChillersHydraulic decoupling Primary-Secondary Decoupled SystemsCheck valves Production loop System Configurations ProductionDistribution-loop benefits of decoupled system arrangement System Configurations DistributionCommon CampusTertiary or distributed Tertiary pumping arrangement Decoupled system-principle of operationTemperature-sensing Flow-based controlFlow-sensing Multiple chilled-water plants on a distribution loop Adding a chillerSubtracting a chiller Double-ended decoupled system Pump control in a double-ended decoupled systemChiller sequencing in a double-ended decoupled system Other plant designs Variable-Primary-Flow SystemsOperational savings of VPF designs Advantages of variable primary flowDispelling a common misconception Chiller selection requirementsFlow, ft.water Flow rate Flow-rate changes that result from isolation-valve operation Managing transient water flowsSystem Configurations Effect of dissimilar evaporator pressure drops System design and control requirementsAccurate flow measurement Bypass flow control Chiller sequencing in VPF systemsFlow-rate-fluctuation examples Adding a chiller in a VPF systemSequencing based on load Subtracting a chiller in a VPF systemSelect slow-acting valves to control the airside coils Other VPF control considerationsConsider a series arrangement for small VPF applications Plant configurationChiller selection Guidelines for a successful VPF systemBypass flow Plant configurationChiller sequencing Airside controlChilled-Water System Variations Heat RecoveryCondenser Free Cooling or Water Economizer Plate-and-frame heat exchangerRefrigerant migration Chilled-Water System VariationsWell, river, or lake water Refrigerant migration chiller in free-cooling modePreferential loading parallel arrangement Preferential LoadingSidestream plate-and-frame heat exchanger Preferential loading sidestream arrangementChilled-Water System Variations Sidestream with alternative fuels or absorptionSidestream system control Preferential loading series arrangementSeries-series counterflow Series-Counterflow ApplicationUnequal Chiller Sizing EvaporatorsCondensers System Issues and Challenges Low ΔT SyndromeAmount of Fluid in the Loop Chiller response to changing conditions System Issues and ChallengesSystem response to changing conditions ExampleContingency Minimum capacity requiredType and size of chiller Alternative Energy Sources System Issues and Challenges Location of equipmentWater and electrical connections Ancillary equipmentPlant Expansion Alternative fuelThermal storage Retrofit Opportunities Applications Outside the Chiller’s RangeFlow rate out of range Precise temperature control System Issues and Challenges Temperatures out of rangePrecise temperature control, multiple chillers System Controls Chilled water reset-raising and loweringChilled-Water System Control Chilled-water pump controlCritical valve reset pump pressure optimization System ControlsNumber of chillers to operate Minimum refrigerant pressure differential Condenser-Water System ControlVFDs and centrifugal chillers performance at 90% load Chillers DifferenceCooling-tower-fan control Condenser-water temperature controlChiller-tower energy consumption Chiller-tower energy balanceChiller-tower-pump balance System Controls Variable condenser water flowEffect of chiller load on water pumps and cooling tower fans Decoupled condenser-water systemCDWP-2 Failure recovery Failure RecoveryConclusion Glossary Pumps system GlossaryGlossary Plant. Idea 88th Annual Conference Proceedings 1997 ReferencesEngineering July References102 Ashrae IndexIndex 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.
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