Effect of chilled-water temperature

Primary System Components

•In a direct-expansion (DX) shell-and-tube evaporator (Figure 3), warmer water fills the shell while the cool, lower-pressure liquid refrigerant flows through the tubes.

Figure 3. Direct-expansion evaporator cut-away

Chilled Water

Supply

Chilled

BafflesWater

Return

Refrigerant

Vapor

Liquid

Refrigerant

Tube Bundle

In either design, there is an approach temperature, which is the temperature difference between the refrigerant and exit water stream temperatures. The approach temperature is a measure of the heat transfer efficiency of the evaporator.

For a given chiller, as the leaving chilled-water temperature drops, the refrigerant temperature and pressure must also drop. Conversely, as the leaving chilled-water temperature rises, so do the refrigerant temperature and pressure. When the leaving chilled-water temperature changes, the work a compressor must do also changes. The effect of leaving chilled-water temperature change on power consumption can be 1.0 to 2.2 percent per degree Fahrenheit [1.8 to 4.0 percent per degree Celsius]. Always consider the energy consumption of the entire system—not only the chiller. It is important to remember that although reducing leaving chilled-water temperature penalizes the chiller, it may reduce the overall system energy because less water is pumped through the system. System interactions are covered in more detail in “System Design Options” on page 27.

Effect of chilled-water flow rate and variation

The evaporator is sensitive to the water flow rate. Excessive flow may result in high water velocity, erosion, vibration, or noise. Insufficient flow reduces heat-transfer efficiency and causes poor chiller performance, which might cause the chiller controls to invoke safeties. Some designers have concerns over low flow rates causing fouling. Generally, as Webb and Li1 noted, these concerns are unwarranted since the chilled-water loop is a closed system, thus reducing the chances of materials entering the system and causing fouling. Chilled-water flow through the evaporator must be kept within specific minimum and maximum limits. Contact the manufacturer for these limits.

SYS-APM001-EN

Chiller System Design and Control

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.

Trane SYS-APM001-EN manual Effect of chilled-water temperature

Models: SYS-APM001-EN

Primary System Components

Figure 3. Direct-expansion evaporator cut-away