Print this page HVAC Multi-Split Variable Refrigerant Flow (VRF) Systems
A. Bhatia, B.E.
Course Outline
The basic principle of operation for variable refrigerant flow (VRF) technology is utilizing a single condensing unit for multiple evaporator units each having dedicated controls. Each indoor unit uses an EEV (electronic expansion valve) to control its refrigerant supply to match the demand of the space it serves. The outdoor unit also varies its output to match the communal demands of the indoor units it serves. Thus, at any point in a system there will be a variable volume of refrigerant flowing. The arrangement provides individualized comfort control, and simultaneous heating and cooling in different zones.
This 2 -hour course provides an overview of VRF system technology.This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.
Learning Objective
At the conclusion of this course, the reader will:
- Understand the difference between multi-split air conditioning system and VRF systems;
- Understand the operating principle of direct expansion split and VRF system;
- Understand the concept of thermal zone;
- Understand how VRF with heat recovery are different from ordinary heat pump systems;
- Understand the operation of thermostatic expansion valve (TXV) and electronic expansion valve (EEV);
- Understand the influence of building characteristics and load profile on selection of VRF system;
- Learn the advantages and application of VRF systems; and
- Understand the design limitations and challenges in design of VRF systems.
Intended Audience
This course is intended for people who plan, design, install, and operate HVAC system for buildings. This course is ideal for building MEP engineers, energy auditors, facility managers, architects, O & M personnel, technicians, construction or building management professionals.
Benefit to Attendees
Attendees of this course will get to know more about VRF system capabilities and limitations during design stage, installation, commissioning and service. The course will be helpful to the professional engineers and amateur engineers who desire to build on their design experience and have learnt the trade informally on the job.
Course Introduction
VRV/VRF technology is based on the simple vapor compression cycle. The systems use multiple compressors, including inverter-driven variable speed units, and pulse modulating expansion vales that deliver variable refrigerant flow to the multiple evaporators. The arrangement provides excellent part-load performance and zoned temperature control, resulting in excellent occupant comfort and energy savings. Both installed costs and energy operating costs are highly application dependent.
Course Content
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HVAC Multi-Split Variable Refrigerant Flow (VRF) Systems
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Course Summary
VRF systems are extremely efficient, reliable, energy saving ways to heat and cool all types of buildings with minimum installation time or disruption.
In VRF system, the refrigerant flow rate is constantly adjusted by an electronic expansion valve and inverter controlled variable speed compressor in response to load variations as rooms require more or less cooling. The system consists of a number of indoor units connected to one or more external condensing units. A control system enables switching between the heating and cooling modes if necessary. In more sophisticated versions, the indoor units may operate in heating or cooling mode independently of others.
VRV/VRF technology is based on the simple vapor compression cycle but the system capabilities and limitations must be fully understood and evaluated carefully to determine its suitability. Before working with VRV/VRF systems it is strongly recommended that manufacturer’s product training be undertaken.
Quiz
Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.
DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.
