Download or read book HVAC Variable Refrigerant Flow VRF Systems written by A. Bhatia and published by CreateSpace. This book was released on 2014-12-06 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: VRF (Variable refrigerant flow) is an air-condition system configuration where there is one outdoor condensing unit and multiple indoor units. The term variable refrigerant flow (VRF) refers to the ability of the system to control the amount of refrigerant flowing to the multiple evaporators (indoor units), enabling the use of many evaporators of differing capacities and configurations connected to single condensing unit. The arrangement provides an individualized comfort control, and simultaneous heating and cooling in different zones. Currently widely applied in large buildings especially in Japan and Europe, these systems are just starting to be introduced in the U.S. The VRF technology/system was developed and designed by Daikin Industries, Japan who named and protected the term variable refrigerant volume (VRV) system so other manufacturers use the term VRF "variable refrigerant flow". In essence both are same. With a higher efficiency and increased controllability, the VRF system can help achieve a sustainable design. Unfortunately, the design of VRF systems is more complicated and requires additional work compared to designing a conventional direct expansion (DX) system. This 3 -hour quick book provides an overview of VRF system technology. Emphasis is placed on the control principles, terminology, basic components, advantages and design limitations. This course is aimed at the personnel who have some limited background in the air conditioning field and is suitable for mechanical, electrical, controls and HVAC engineers, architects, building designers, contractors, estimators, energy auditors and facility managers.The course includes a multiple-choice quiz consisting of fifteen (15) questions at the end. Learning ObjectiveAt 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;* Understand the design limitations and challenges in design of VRF systems.

Download or read book Variable Refrigerant Flow Systems written by Napoleon Enteria and published by Springer Nature. This book was released on 2023-01-31 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Dynamic Modeling and Controls of Variable Refrigerant Flow Systems written by Liujia Dong and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Building heating ventilation and air conditioning (HVAC) systems have significant impact on the energy consumption of residential and commercial buildings. The Variable Refrigerant Flow (VRF) systems, by distributing refrigerant instead of air flow, have emerged as an appealing class of HVAC system that features quieter operation, higher flexibility, and lower cost of installation and maintenance. However, such systems also present higher challenges for controls that can realize its achievable performance. This dissertation research proposes to investigate the dynamic simulation modeling and modelfree control strategies for energy efficient operation of VRF systems with single or multiple outdoor units (ODUs) under fluctuating and uncertain load and ambient conditions. Modelica based dynamic simulation models are developed for VRF systems of different configurations, which involve modeling of indoor units (IDUs), ODUs, and various control valves for thermal regulation. Motivated by a preliminary study on applying multi-variable extremum seeking control (ESC) for an air-source heat pump (ASHP) system, a model-free self-optimizing control strategy is investigated for efficient operation of a multi-functional VRF system under both heat pump modes and heat recovery modes. With the feedback of the total power only, the multi-variable ESC takes different combinations of manipulated inputs, including IDU superheat setpoints, compressor pressure setpoints, ODU fan speed, and ODU superheat setpoint. Input selection is carried out based on their respective impact on the total power. To realize automatic and smooth switching between different operation modes of multi-functional VRF system, the mode switching strategy is proposed. Whether to turn on or off an IDU is determined by the zone temperature and a preset hysteresis band about the temperature setpoint. Based on the thermodynamic analysis, a decision variable for determining the mode of ODU heat exchanger (HX) is proposed as the ODU-HX air-side temperature differential normalized by the dimensionless outdoor unit fan speed. For the smooth switching between two compressor pressure controllers, two bumpless transfer methods are applied. The simulation results validate the effectiveness of the proposed strategy and performance of bumpless transfer strategies. For the multi-ODU VRF systems, an integrated efficiency operation strategy is proposed to optimize the energy efficiency, which consists of three respects: i) for a given operating condition, a multi-variable ESC strategy is used to optimize the settings of manipulated inputs of operating ODUs, by use of a load-sharing valve array and feedback of the normalized total power; ii) a model-free ODU compressor staging strategy with ESC integrated control logic; and iii) a modelfree ODU heat exchanger mode switching strategy with ESC integrated control logic. For staging on additional ODU compressor, the saturated operation of compressor speed (i.e. saturated to the higher limit) is used as the indicating variable. With ESC-alike real-time optimization strategy in operation, the least efficient compressor would be driven, which will then be staged off. As for automatic mode switch of ODU heat exchangers during heat recovery operation, the saturation of IDU EEV opening is utilized as the indicating variable, and the ODU heat exchanger (or fan-coil unit) with least efficiency under ESC operation will switch its operational mode. Similar to many other HVAC systems, the ESC operation of VRF systems is subject to state and/or input constraints. In this dissertation research, the general problem of constrained ESC is studied. The penalty-functions based framework of constrained ESC is studied. The dither-demodulation design is modified for penalty-function based ESC with assumption of Wiener-Hammerstein system composition. An online penalty-weight adaptation scheme is proposed with online Hessian estimation, and its convergence analysis is conducted in the context of numerical optimization ESC (NOESC).

Download or read book Comparative Analysis of the VRF System and Conventional HVAC Systems Focused on Life cycle Cost written by Jaesuk Park and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As concern for the environment has been dramatically raised over the recent decade, all fields have increased their efforts to reduce impact on environment. The field of construction has responded and started to develop the building performance strategies as well as regulations to reduce the impact on the environment. HVAC systems are obviously one of the key factors of building energy consumption. This study investigates the system performance and economic value of variable refrigerant flow (VRF) systems relative to conventional HVAC systems by comparing life-cycle cost of VRF systems to that of conventional HVAC systems. VRF systems consist mainly of one outdoor unit and several indoor units. The outdoor unit provides all indoor units with cooled or heated refrigerant; with these refrigerants, each indoor unit serves one zone, delivering either heating or cooling. Due to its special configuration, the VRF system can cool some zones and heat other zones simultaneously. This comparative analysis covers six building types--medium office, standalone retail, primary school, hotel, hospital, and apartment--in a eleven climate zones--1A Miami, 2A Houston, 2B Phoenix, 3A Atlanta, 3B Las Vegas, 3C San Francisco, 4A Baltimore, 4B Albuquerque, 4C Seattle, 5A Chicago, and 5B Boulder. Energy simulations conducted by EnergyPlus are done for each building type in each climate zone. Base cases for each simulation are the reference models that U.S. Department of Energy has developed, whereas the alternative case is the same building in the same location with a VRF system. The life-cycle cost analysis provides Net Savings, Saving to- Investment ratio, and payback years. The major findings are that the VRF system has an average of thirty-nine percent HVAC energy consumption savings. As for the results of the life-cycle cost analysis, the average of simple payback period is twelve years.

Download or read book Refrigeration Air Conditioning and Heat Pumps written by G F Hundy and published by Butterworth-Heinemann. This book was released on 2016-03-07 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book VRF Technology written by Charles Nehme and published by Independently Published. This book was released on 2024-02-15 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a world increasingly aware of energy efficiency, comfort, and the need for sustainable solutions, Variable Refrigerant Flow (VRF) systems are emerging as a transformative force in climate control. This book delves into the heart of VRF technology, offering a comprehensive guide for all who seek to understand, design, or implement these innovative systems. Whether you're a seasoned building professional or a homeowner curious about cutting-edge HVAC options, this book welcomes you. We'll embark on a journey that demystifies the complexity of VRF systems, exploring their intricate components, operational principles, and diverse applications. Why VRF? The need for a paradigm shift in climate control solutions is undeniable. Traditional systems often struggle with inefficiencies, inflexible zoning, and bulky installations. VRF technology addresses these challenges head-on, offering: Unmatched energy efficiency: VRF systems boast inverter-driven compressors and sophisticated control systems, leading to significant energy savings and reduced environmental impact. Zonal comfort control: Each space within a building can be individually conditioned, ensuring occupant comfort while minimizing wasted energy. Flexible design and installation: VRF systems adapt to diverse architectural constraints with their branch-based piping network, requiring minimal ductwork and offering space-saving advantages. Cost-effectiveness: While requiring some initial investment, VRF systems often deliver long-term cost savings through energy efficiency, reduced maintenance, and extended longevity. Beyond the Hype: This book will not simply tout the benefits of VRF systems. We'll delve into their limitations, design considerations, and installation complexities, ensuring you make informed decisions. Understanding the challenges alongside the advantages empowers you to navigate the VRF landscape with confidence.

Download or read book A New Model to Simulate Energy Performance of VRF Systems written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents a new model to simulate energy performance of variable refrigerant flow (VRF) systems in heat pump operation mode (either cooling or heating is provided but not simultaneously). The main improvement of the new model is the introduction of the evaporating and condensing temperature in the indoor and outdoor unit capacity modifier functions. The independent variables in the capacity modifier functions of the existing VRF model in EnergyPlus are mainly room wet-bulb temperature and outdoor dry-bulb temperature in cooling mode and room dry-bulb temperature and outdoor wet-bulb temperature in heating mode. The new approach allows compliance with different specifications of each indoor unit so that the modeling accuracy is improved. The new VRF model was implemented in a custom version of EnergyPlus 7.2. This paper first describes the algorithm for the new VRF model, which is then used to simulate the energy performance of a VRF system in a Prototype House in California that complies with the requirements of Title 24? the California Building Energy Efficiency Standards. The VRF system performance is then compared with three other types of HVAC systems: the Title 24-2005 Baseline system, the traditional High Efficiency system, and the EnergyStar Heat Pump system in three typical California climates: Sunnyvale, Pasadena and Fresno. Calculated energy savings from the VRF systems are significant. The HVAC site energy savings range from 51 to 85percent, while the TDV (Time Dependent Valuation) energy savings range from 31 to 66percent compared to the Title 24 Baseline Systems across the three climates. The largest energy savings are in Fresno climate followed by Sunnyvale and Pasadena. The paper discusses various characteristics of the VRF systems contributing to the energy savings. It should be noted that these savings are calculated using the Title 24 prototype House D under standard operating conditions. Actual performance of the VRF systems for real houses under real operating conditions will vary.

Download or read book Energy Performance Evaluation and Economic Analysis of Variable Refrigerant Flow Systems written by Dongsu Kim and published by . This book was released on 2019 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Application and Design of Air to air Variable Refrigerant Flow Systems written by Paul Wicoff and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report addresses the operation, use, and design of air-to-air variable refrigerant flow systems, also known as VRF. Relatively new to the United States, these HVAC systems have potential to reduce energy consumption and utility costs in the correct applications. Although useful in many applications, the best building types for VRF are those requiring a large number of zones and with low ventilation air requirements. The report explains design and system selection considerations and accordingly presents two flowcharts to help designers implement this system. To show how the system compares to traditional technologies in terms of efficiency and cost, the report presents results from several studies comparing VRF to other systems. In addition, an energy modeling study is conducted to clarify the effect of climate on the system; this study established air-to-air VRF as having highest energy consumption in dry, southern climates, based on energy use and operating costs. With this report, HVAC designers can learn when air-to-air VRF is an acceptable method for providing heating and cooling in a building.

Download or read book Variable Air Volume Systems written by Leo A. Meyer and published by HVAC Books—Best on the Web. This book was released on 1998 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Guide to variable refrigerant flow VRF air conditioning written by D. et al Arnold and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides guidance relevant to those with a role in system design, installation and operation, covering how variable refrigerant flow (VRF) systems work and how they can be designed so that they operate in a highly efficient way.

Download or read book Variable Refrigerant Flow VRF Air Conditioning System written by Lip Wai Tan and published by . This book was released on 2008 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Variable Refrigerant Flow VRF Air Conditioning System written by Jamil Lahani and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heating with Renewable Energy written by John Siegenthaler and published by Cengage Learning. This book was released on 2016-02-10 with total page 864 pages. Available in PDF, EPUB and Kindle. Book excerpt: Whether you are preparing for a career in the building trades or are already a professional contractor, this practical book will help you develop the knowledge and skills you need to merge renewable heat sources (such as solar thermal collectors, hydronic heat pumps, and wood-fired boilers) with the latest hydronics hardware and low temperature distribution systems to assemble efficient and reliable heating systems. Easy to understand and packed with full color illustrations that provide detailed piping and control schematics and how to information you'll use on every renewable energy system, this one-of-a-kind book will help you diversify your expertise over a wide range of heat sources. Important Notice: Media content referenced within the product description or the product text may not be available in the ebook version.

Download or read book HVAC Principles and Systems written by Dr. Ilango Sivaraman and published by Dr Ilango Sivaraman. This book was released on 2019-06-02 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: HVAC - Heating, Ventilation and Air conditioning systems and applications are used everyday by a substantial population in developed and developing countries. Apparently most of the users are not aware of the types and the concepts of these systems. Perhaps many of them feel that there is no need to understand the concepts and applications. However, students/ Technicians and others who would like to learn and deal with the systems need an introductory level book, that would initiate them into this field. This book is planned to include fundamental concepts of HVAC systems and hopefully meet the expectations of students aspiring to learn in general about these systems.

Download or read book ASHRAE Handbook Refrigeration 2014 written by Ashrae and published by . This book was released on 2014-01-01 with total page 784 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 2014 ASHRAE Handbook--Refrigeration covers the refrigeration equipment and systems for applications other than human comfort. This volume includes data and guidance on cooling, freezing, and storing food; industrial and medical applications of refrigeration; and low-temperature refrigeration.The 2014 ASHRAE Handbook--Refrigeration CD, in both I-P and SI editions, contains PDFs of chapters easily viewable using Adobe Reader. This product must be installed on user's computer. Product cannot be read directly from CD and is not compatible with mobile devices. Opened software cannot be returned for refund or credit.

Download or read book Technical Subtopic 2 1 written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The University of Central Florida/Florida Solar Energy Center, in cooperation with the Electric Power Research Institute and several variable-refrigerant-flow heat pump (VRF HP) manufacturers, provided a detailed computer model for a VRF HP system in the United States Department of Energy's (U.S. DOE) EnergyPlus? building energy simulation tool. Detailed laboratory testing and field demonstrations were performed to measure equipment performance and compare this performance to both the manufacturer's data and that predicted by the use of this new model through computer simulation. The project goal was to investigate the complex interactions of VRF HP systems from an HVAC system perspective, and explore the operational characteristics of this HVAC system type within a laboratory and real world building environment. Detailed laboratory testing of this advanced HVAC system provided invaluable performance information which does not currently exist in the form required for proper analysis and modeling. This information will also be useful for developing and/or supporting test standards for VRF HP systems. Field testing VRF HP systems also provided performance and operational information pertaining to installation, system configuration, and operational controls. Information collected from both laboratory and field tests were then used to create and validate the VRF HP system computer model which, in turn, provides architects, engineers, and building owners the confidence necessary to accurately and reliably perform building energy simulations. This new VRF HP model is available in the current public release version of DOE?s EnergyPlus software and can be used to investigate building energy use in both new and existing building stock. The general laboratory testing did not use the AHRI Standard 1230 test procedure and instead used an approach designed to measure the field installed full-load operating performance. This projects test methodology used the air enthalpy method where relevant air-side parameters were controlled while collecting output performance data at discreet points of steady-state operation. The primary metrics include system power consumption and zonal heating and cooling capacity. Using this test method, the measured total cooling capacity was somewhat lower than reported by the manufacturer. The measured power was found to be equal to or greater than the manufacturers indicated power. Heating capacity measurements produced similar results. The air-side performance metric was total cooling and heating energy since the computer model uses those same metrics as input to the model. Although the sensible and latent components of total cooling were measured, they are not described in this report. The test methodology set the thermostat set point temperature very low for cooling and very high for heating to measure full-load performance and was originally thought to provide the maximum available capacity. Manufacturers stated that this test method would not accurately measure performance of VRF systems which is now believed to be a true statement. Near the end of the project, an alternate test method was developed to better represent VRF system performance as if field installed. This method of test is preliminarily called the Load Based Method of Test where the load is fixed and the indoor conditions and unit operation are allowed to fluctuate. This test method was only briefly attempted in a laboratory setting but does show promise for future lab testing. Since variable-speed air-conditioners and heat pumps include an on-board control algorithm to modulate capacity, these systems are difficult to test. Manufacturers do have the ability to override internal components to accommodate certification procedures, however, it is unknown if the resulting operation is replicated in the field, or if so, how often. Other studies have shown that variable-speed air-conditioners and heat pumps do out perform their single-speed coun ...