What You Will Learn
Many large buildings, campuses, and other facilities have plants that make chilled water and distribute it to air-handling units (AHUs) and other cooling equipment. The design, operation, and maintenance of these CHW plants has a very large impact on building energy use and energy operating cost. The intent of this course is to provide tools and guidance to engineers so that the plants they design have a near optimum balance of first costs and future operating costs. The course can also be used by plant operators to understand and resolve operational problems and improve energy efficiency through controls optimization. After completing the course, you should have an understanding of the following:
- CHW plant peak loads and annual cooling load profiles and how they affect plant design and equipment capacity
- An overview of the primary equipment, as well as essential information on how the components relate to one another, how they are controlled, and what their physical and operational limitations are
- Piping layouts and design issues related to CHW distribution systems and condenser water systems
- Procedures and analysis techniques for optimizing the design to minimize first costs and operating costs (in particular, energy costs) over the plant’s life cycle
- An approach to selecting chillers using life-cycle cost techniques
- General factors that should be considered when designing and installing a CHW plant building automation system (BAS) and suggested control sequences
- Elements of the commissioning (Cx) process that are key to ensuring that chiller plants meet their design intent
Course Content
Loads. Chapter 2 discusses the nature of CHW loads and how they should be considered in the design of CHW plants. In the past, most engineers have only estimated the peak or maximum load. However, accounting for the time pattern of loads can be just as important. Methods of calculating peak loads and hourly loads are reviewed. These include site measurements (for existing facilities), computer simulations, rules of thumb, and prototype buildings.
Equipment. Chapter 3 reviews some basics on chillers, cooling towers, pumps, and other plant equipment. This chapter discusses the basic refrigeration cycle, water chillers, cooling towers, air-cooled condensers, pumps, and variable-speed drives.
Distribution Systems. Chapter 4 discusses different ways of arranging CHW equipment in the system to meet loads while achieving energy efficiency and operational simplicity. The pros and cons of constant-flow and variable-flow systems are discussed along with different primary-only and primary/secondary pumping systems.
Optimizing Design. Chapter 5 provides procedures and analysis techniques for optimizing CHW plant design. Topics include optimizing the selection of distribution systems and optimizing the selection of CHW and condenser water design temperatures and pipe sizes. A spreadsheet for sizing piping and calculating pump head is provided at ashrae.org/CHWSDL (Pipe Size Optimization Tool spreadsheet). Recommendations were developed from in-depth life-cycle cost analysis of typical chiller plants and are provided as easy-to-use rules of thumb and procedures to simplify plant design while still achieving near-optimum life-cycle performance.
Chiller Procurement. Chapter 6 discusses strategies for evaluating chiller options and selecting and procuring an energy-efficient and cost-effective chiller. Case studies of the chiller selection process are provided. Sample chiller bid forms are also provided (Chiller Bid Form and Simplified Chiller Bid Form).
Controls. Chapter 7 explores the many design and performance issues related to controls and instrumentation of CHW plants. Topics include types of flow and temperature sensors, styles of and selection criteria for control valves, controller requirements and interfacing issues, performance monitoring, and recommended near-optimum control sequences for CHW plants, including all-variable-speed plants where all components have variable-speed drives.
Commissioning. Chapter 8 discusses key elements of the commissioning process, addressing in detail sequence of operation review, point-to-point checkout, functional testing, and trend reviews.
Supplemental Files. Supplemental material for this SDL is available at ashrae.org/CHWSDL. These files include a chiller bid form, a simplified chiller bid form, and a pipe size optimization tool.
Who Should Enroll in this Course?
This is an excellent course for anyone who needs information on air distribution systems. You will benefit from this course if you are:
- A recent engineering graduate working in the HVAC&R industry.
- An experienced engineer who has entered the HVAC&R industry from another engineering field.
- An architect, engineer, technician, or construction or building management professional who wants to increase your knowledge of air distribution systems.
Getting Started: