Variable refrigerant flow
Variable refrigerant flow (VRF), also known as variable refrigerant volume (VRV), is an
Description
VRFs are typically installed with an
VRFs come in two system formats, two pipe and three pipe systems. In a heat pump two pipe system all of the zones must either be all in cooling or all in heating. Heat Recovery (HR) systems have the ability to simultaneously heat certain zones while cooling others; this is usually done through a three pipe design, with the exception of Mitsubishi, Carrier and LG whose systems are able to do this with a two pipe system using a branch circuit (BC) controller to the individual indoor evaporator zones. In this case the heat extracted from zones requiring cooling is put to use in the zones requiring heating. This is made possible because the heating unit is functioning as a condenser, providing sub-cooled liquid back into the line that is being used for cooling. While the heat recovery system has a greater initial cost, it allows for better zoned thermal control of a building and overall greater efficiencies.[6] In heat recovery VRF systems, some of the indoor units may be in cooling mode while others are in heating mode, reducing energy consumption. If the coefficient of performance in cooling mode of a system is 3, and the coefficient of performance in heating mode is 4, then heat recovery performance can reach more than 7. While it is unlikely that this balance of cooling and heating demand will happen often throughout the year, energy efficiency can be greatly improved when the scenario occurs.[7]
VRF systems may be air or water cooled. If air cooled, VRF condensing units are exposed to outside air and may be outdoors, and condensing units are the size of large refrigerators, since they need to contain a large condenser (heat exchanger) which has a large surface area to transfer heat to the surrounding air, because air doesn't have a high heat capacity[8] and has a low density, volumetric thermal capacity and thermal conductivity thus needing to transfer heat into a large amount of air volume at once. If water cooled, the condensing units are placed indoors and are much smaller and cooled with water by a closed type or circuit cooling tower or dry cooler.
Japan
VRF systems have been used in Japan since the 1980s. By 2007, in Japan, VRFs are used in 50% of midsize office buildings (up to 70,000 ft2 or 6,500 m2) and 33% of large commercial buildings (more than 70,000 ft2 or 6,500 m2).[6]
Home automation integration
There are dedicated gateways that connect VRFs with
Primary manufacturers
Japan:
- Daikin
- Panasonic
- Mitsubishi Heavy Industries
- Fujitsu (Fujitsu General)
- Hitachi (Now Johnson Controls-Hitachi (Air Conditioning) (Jci-Hitachi)
- Mitsubishi Electric
- Finpower Aircon LLC
- Toshiba
- Yanmar (gas heat pumps)
- Sharp(former)
- Sanyo(now Panasonic)
- Toshiba Carrier(Former Air-conditioning & Heating International (AHI)(AHI-Carrier/Toshiba) (Toshiba-Carrier)[11][12] (As of 2018, the joint venture(s) seem to have been broken up, as Carrier now manufactures VRF systems of its own and Toshiba's websites no longer show the Carrier logo in their product images (which is not the case in some of Carrier's images[13][14]) and web pages, and the AHI-Carrier(Toshiba) website has not been updated since 2016)
Korea:
India:
Bangladesh:
- Walton Hi-Tech Industries Limited[15]
Italy:
United States:
- Ephoca
- Innovair
- Carrier (Made by Toshiba)
- York International(Made by Hitachi)
- Trane (formerly made by Samsung, now made by Mitsubishi Electric)
- Lennox
- Afka Group (American Pro)
- CIAC(Carrier)
France:
China/Other:
References
- ^ a b Thornton, Brian (December 2012). Variable Refrigerant Flow Systems (PDF). General Services Administration (Report). US Federal Government. Archived from the original (PDF) on 2022-01-20. Retrieved 2013-08-06.
- ^ "VRF – "Reason to choose VRF HVAC Technology" – 22-7 Website". Retrieved 2019-09-05.
- ^ "Introduction of Heat Recovery Chiller Control and Water System Design" (PDF). Retrieved 2024-01-13.
- ^ Felt, Justin (2017-12-21). "The Emergence of VRF as a Viable HVAC Option". Buildings. Endeavor Business Media. Archived from the original on 2023-02-10.
- ^ "Variable Refrigerant Flow".
- ^ a b Goetzler (April 2007). "Variable Refrigerant Flow Systems". ASHRAE Journal: 24–31.
- ^ Rostamabadi, Mehrdad (2017). VRF HVAC Systems. Shafaf.
- ^ GF. Hundy, A.R. Trott, T.C. Welch, Chapter 6 - Condensers and Cooling Towers, Editor(s): G.F. Hundy, A.R. Trott, T.C. Welch, Refrigeration, Air Conditioning and Heat Pumps (Fifth Edition), Butterworth-Heinemann, 2016, Pages 99-120, ISBN 9780081006474, https://doi.org/10.1016/B978-0-08-100647-4.00006-1
- ^ "Cool Automation's CoolMasterNet Features IP Connectivity, Multi-Brand HVAC Support". CE Pro. Retrieved 16 November 2015.
- ^ "Air Condition Repair". Tuesday, 10 August 2021
- ^ "Toshiba Carrier Global | Air conditioner for residential, commercial and industrial uses". www.toshiba-carrier.co.jp.
- ^ "AHI Carrier Contacts". www.ahi-toshiba.com.
- ^ "Toshiba Carrier Ductless Heat Pump System - RAS-LAV/LKV | Carrier - Home Comfort". Carrier.
- ^ "Toshiba Carrier Variable Refrigerant Flow Systems | Carrier Commercial Systems North America". Carrier.
- ^ "VRF IFM Series". waltonbd.com. Retrieved 2023-07-19.
- ^ "VRF: Bosch Enters the Market". rac. 15 January 2016.
- ^ "Bosch enters VRF". Cooling Post. April 1, 2015.
- ^ "VRF systems | Products |". Buderus.