Energy Performance Evaluation and Economic Analysis of Variable Refrigerant Flow Systems

Energy Performance Evaluation and Economic Analysis of Variable Refrigerant Flow Systems
Author: Dongsu Kim
Publisher:
Total Pages: 138
Release: 2019
Genre:
ISBN:

This study evaluates energy performance and economic analysis of variable refrigerant flow (VRF) systems in U.S. climate locations using widely-accepted whole building energy modeling software, EnergyPlus. VRF systems are known for their high energy performance and thus can improve energy efficiency in buildings. To evaluate the energy performance of a VRF system, energy simulation modeling and calibration of a VRF heat pump (HP) type system is performed using the EnergyPlus program based on measured data collected from an experimental facility at Oak Ridge National Laboratory (ORNL). In the calibration procedures, the energy simulation model is calibrated, according to the ASHRAE Guideline 14-2014, under cooling and heating seasons. After a proper calibration of the simulation model, the VRF HP system is placed in U.S. climate locations to evaluate the performance variations in different weather conditions. An office prototype building model, developed by the U.S. Department of Energy (DOE), is used with the VRF HP system in this study. This study also considers net-zero energy building (NZEB) design of VRF systems with a distributed photovoltaic (PV) system. The NZEB concept has been considered as one of the remedies to reduce electric energy usages and achieve high energy efficiency in buildings. Both the VRF HP and VRF heat recovery (HR) system types are considered in the NZEB design, and a solar PV system is utilized to enable NZEB balances in U.S. climate locations by assuming that net-metering available within the electrical grid-level. In addition, this study conducts life cycle cost analysis (LCCA) of NZEBs with VRF HP and HR systems. LCCA provides present values at a given study period, discounted payback period, and net-savings between VRF HP and HR systems in U.S. climate locations. Preliminary results indicate that the simulated VRF HP system can reasonably predict the energy performance of the actual VRF HP system and reduce between 15-45% for HVAC site energy uses when compared to a VAV system in U.S. climate locations. The VRF HR system can be used to lower building energy demand and thus achieve NZEB performance effectively in some hot and mild U.S. climate locations.

Variable Refrigerant Flow Systems

Variable Refrigerant Flow Systems
Author: Napoleon Enteria
Publisher: Springer Nature
Total Pages: 251
Release: 2023-01-31
Genre: Science
ISBN: 9811968330

This book compiles the latest research, development, and application of VRF systems with contributions from various experts who pioneered and contributed to the development of the VRF system. This book presents the fundamental issues related to the real application and behaviour of the VRF system based on the long-term monitoring of the installed system. With our experience of pandemic which COVID-19 is an airborne, the spread of the virus is very fast. With this, the heating, ventilating and air-conditioning (HVAC) system is a major player in the maintenance and control of indoor environment to minimize the spread of the virus. As the variable refrigerant flow (VRF) system is a versatile HVAC system in which it can operate at different conditions, the application of the VRF system is very important to control the indoor environmental conditions. Thus, the publication of this book is important with the present situation and the future possible situation which the control of indoor spaces is very important. With this, this book will serve as a reference for building designer, contractors, building regulators and students.

Evaluation of Variable Refrigerant Flow Systems Performance and the Enhanced Control Algorithm on Oak Ridge National Laboratory S Flexible Research Platform

Evaluation of Variable Refrigerant Flow Systems Performance and the Enhanced Control Algorithm on Oak Ridge National Laboratory S Flexible Research Platform
Author:
Publisher:
Total Pages: 79
Release: 2015
Genre:
ISBN:

A research project "Evaluation of Variable Refrigerant Flow (VRF) Systems Performance and the Enhanced Control Algorithm on Oak Ridge National Laboratory's (ORNL's) Flexible Research Platform" was performed to (1) install and validate the performance of Samsung VRF systems compared with the baseline rooftop unit (RTU) variable-air-volume (VAV) system and (2) evaluate the enhanced control algorithm for the VRF system on the two-story flexible research platform (FRP) in Oak Ridge, Tennessee. Based on the VRF system designed by Samsung and ORNL, the system was installed from February 18 through April 15, 2014. The final commissioning and system optimization were completed on June 2, 2014, and the initial test for system operation was started the following day, June 3, 2014. In addition, the enhanced control algorithm was implemented and updated on June 18. After a series of additional commissioning actions, the energy performance data from the RTU and the VRF system were monitored from July 7, 2014, through February 28, 2015. Data monitoring and analysis were performed for the cooling season and heating season separately, and the calibrated simulation model was developed and used to estimate the energy performance of the RTU and VRF systems. This final report includes discussion of the design and installation of the VRF system, the data monitoring and analysis plan, the cooling season and heating season data analysis, and the building energy modeling study.

Refrigeration, Air Conditioning and Heat Pumps

Refrigeration, Air Conditioning and Heat Pumps
Author: G F Hundy
Publisher: Butterworth-Heinemann
Total Pages: 512
Release: 2016-03-07
Genre: Science
ISBN: 0081006667

Refrigeration, Air Conditioning and Heat Pumps, Fifth Edition, provides a comprehensive introduction to the principles and practice of refrigeration. Clear and comprehensive, it is suitable for both trainee and professional HVAC engineers, with a straightforward approach that also helps inexperienced readers gain a comprehensive introduction to the fundamentals of the technology. With its concise style and broad scope, the book covers most of the equipment and applications professionals will encounter. The simplicity of the descriptions helps users understand, specify, commission, use, and maintain these systems. It is a must-have text for anyone who needs thorough, foundational information on refrigeration and air conditioning, but without textbook pedagogy. It includes detailed technicalities or product-specific information. New material to this edition includes the latest developments in refrigerants and lubricants, together with updated information on compressors, heat exchangers, liquid chillers, electronic expansion valves, controls, and cold storage. In addition, efficiency, environmental impact, split systems, retail refrigeration (supermarket systems and cold rooms), industrial systems, fans, air infiltration, and noise are also included. Full theoretical and practical treatment of current issues and trends in refrigeration and air conditioning technology Meets the needs of industry practitioners and system designers who need a rigorous, but accessible reference to the latest developments in refrigeration and AC that is supported by coverage at a level not found in typical course textbooks New edition features updated content on refrigerants, microchannel technology, noise, condensers, data centers, and electronic control

Energy Simulation of Integrated Multiple-Zone Variable Refrigerant Flow System

Energy Simulation of Integrated Multiple-Zone Variable Refrigerant Flow System
Author:
Publisher:
Total Pages:
Release: 2013
Genre:
ISBN:

We developed a detailed steady-state system model, to simulate the performance of an integrated five-zone variable refrigerant flow (VRF)heat pump system. The system is multi-functional, capable of space cooling, space heating, combined space cooling and water heating, and dedicated water heating. Methods were developed to map the VRF performance in each mode, based on the abundant data produced by the equipment system model. The performance maps were used in TRNSYS annual energy simulations. Using TRNSYS, we have successfully setup and run cases for a multiple-split, VRF heat pump and dehumidifier combination in 5-zone houses in 5 climates that control indoor dry-bulb temperature and relative humidity. We compared the calculated energy consumptions for the VRF heat pump against that of a baseline central air source heat pump, coupled with electric water heating and the standalone dehumidifiers. In addition, we investigated multiple control scenarios for the VRF heat pump, i.e. on/off control, variable indoor air flow rate, and using different zone temperature setting schedules, etc. The energy savings for the multiple scenarios were assessed.

Multiple-Zone Variable Refrigerant Flow System Modeling and Equipment Performance Mapping

Multiple-Zone Variable Refrigerant Flow System Modeling and Equipment Performance Mapping
Author:
Publisher:
Total Pages:
Release: 2012
Genre:
ISBN:

We developed a variable refrigerant flow (VRF) vapor compression system model, which has five indoor units, one outdoor unit and one water heater. The VRF system can run simultaneous space conditioning (cooling or heating) and water heating. The indoor units and outdoor unit use fin- & -tube coil heat exchangers, and the water heater uses a tube-in-tube heat exchanger. The fin- & -tube coil heat exchangers are modeled using a segment-by-segment approach and the tube-in-tube water heater is modeled using a phase-by-phase approach. The compressor used is a variable-speed rotary design. We calibrated our model against a manufacturer s product literature. Based on the vapor compression system model, we investigated the methodology for generating VRF equipment performance maps, which can be used for energy simulations in TRNSYS and EnergyPlus, etc. In the study, the major independent variables for mapping are identified and the deviations between the simplified performance map and the actual equipment system simulation are quantified.