DOCSLIB.ORG

Dew Point Evaporative Comfort Cooling

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Dew Point Evaporative Comfort Cooling Dew Point Evaporative Comfort Cooling Energy and Water Projects Demonstration Plan SI-0821 TP-7A40-56256-1 November 2012 Jesse Dean, Lesley Herrmann, Eric Kozubal, and Jesse Geiger (National Renewable Energy Laboratory) Mark Eastment (Eastment Consulting Inc.) Steve Slayzak (Coolerado) Link to Summary Report NOTICE This manuscript has been authored by employees of the Alliance for Sustainable Energy, LLC (“Alliance”) under Contract No. DE-AC36-08GO28308 with the U.S. Department of Energy (“DOE”). The work described in this report (NREL/TP-7A40-56256) was funded under task number WFG7.1000. This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Available electronically at http://www.osti.gov/bridge Available for a processing fee to U.S. Department of Energy and its contractors, in paper, from: U.S. Department of Energy Office of Scientific and Technical Information P.O. Box 62 Oak Ridge, TN 37831-0062 phone: 865.576.8401 fax: 865.576.5728 email: mailto:[email protected] Available for sale to the public, in paper, from: U.S. Department of Commerce National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 phone: 800.553.6847 fax: 703.605.6900 email: [email protected] online ordering: http://www.ntis.gov/help/ordermethods.aspx Printed on paper containing at least 50% wastepaper, including 10% post-consumer waste. ii ACKNOWLEDGMENTS The authors would like to thank the ESTCP project team members for their creativity, persistence, and willingness to support this project. Scott Clark, the Energy Program Coordinator for Fort Carson, was instrumental in setting up the demonstration and has provided countless hours assisting with the installation of the data acquisition system and multiyear performance testing. Fort Carson engineers worked with the project partners to design and integrate the Coolerado units into five facilities and designed an innovative rain water catchment system for four units at the Theater. Mountain Energy Partnership provided invaluable assistance with the design and installation of the data acquisition system, as well as data analysis support. Onsite heating, ventilation, and air-conditioning technicians diligently recorded operation and maintenance activities and provided valuable insights into operation and maintenance costs of the units. Several members of the Coolerado team, including Tim Heaton, Steve Slayzak, Leland Gillian, and Daniel Zube, also went out of their way to accommodate the, requests of the Fort Carson and NREL staff members. Various members of NREL’s Commercial Buildings Research team, including James Page, Andrew Parker, Michael Deru, and Brent Griffith, provided laboratory and field testing assistance and modeling support. Finally, the project would not have been possible without financial support from ESTCP program, whose members also provided valuable insights into the types of data analysis procedures and results that would be most beneficial to DoD facilities and engineers. iii ACRONYMS AND ABBREVIATIONS AHU air handling unit ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers Btu British thermal units cfm cubic feet per minute CT current transducer CoC cycle of concentration COP coefficient of performance CRAC computer room air-conditioning DAS data acquisition system DAT discharge air temperature DC-kW direct-current kilowatt DEC direct evaporative cooler, direct evaporative cooling DoD U.S. Department of Defense DX direct expansion EA exhaust air EAT exhaust air temperature ECM electronically commutated motor EER energy efficiency ratio eGrid Emissions & Generation Resource Integrated Database EISA Energy Independence and Security Act of 2007 E.O. Executive Order ESTCP Environmental Security Technology Certification Program EUI energy use intensity HMX heat mass exchanger hp horsepower HVAC heating, ventilating, and air-conditioning IEC indirect evaporative cooler, indirect evaporative cooling IEER integrated energy efficiency ratio kW kilowatt kWh kilowatt-hour L liter MCDB mean coincident dry bulb MMBtu million British thermal units NERC North American Reliability Corporation NREL National Renewable Energy Laboratory NPV net present value OA outside air OAR outside air ratio OAT outside air temperature ppm parts per million RA return air RAT return air temperature iv RH relative humidity RMSE root mean square error RTU rooftop unit SA supply air SAT supply air temperature SHR sensible heat ratio SP static pressure SPP simple payback TDS total dissolved solids TTF Thermal Test Facility TMY typical meteorological year W Watt v TABLE OF CONTENTS ACKNOWLEDGMENTS ....................................................................................................................... III ACRONYMS AND ABBREVIATIONS ................................................................................................. IV TABLE OF CONTENTS ......................................................................................................................... VI LIST OF FIGURES ................................................................................................................................... X LIST OF TABLES ................................................................................................................................. XIV EXECUTIVE SUMMARY ........................................................................................................................ 1 1.0 INTRODUCTION .............................................................................................................................. 4 1.1 BACKGROUND ............................................................................................................................. 4 1.2 OBJECTIVES OF THE DEMONSTRATION ................................................................................ 4 1.3 REGULATORY DRIVERS ............................................................................................................ 5 2.0 TECHNOLOGY DESCRIPTION .................................................................................................... 6 2.1 EVAPORATIVE COOLING ........................................................................................................... 6 2.2 TECHNOLOGY OVERVIEW ........................................................................................................ 7 2.2.1 How It Works ........................................................................................................................... 8 2.2.2 Products ................................................................................................................................ 12 2.3 TECHNOLOGY DEVELOPMENT .............................................................................................. 13 2.4 ADVANTAGES AND LIMITATIONS OF THE TECHNOLOGY .............................................. 14 2.5 COOLERADO DESIGN CONSIDERATIONS ............................................................................ 16 2.6 COOLERADO APPLICATIONS .................................................................................................. 17 2.6.1 Through-the-Wall Zone Cooler ............................................................................................. 17 2.6.2 Outside Air Pre-conditioner .................................................................................................. 18 2.6.3 Zone Cooler with Return Air ................................................................................................. 19 2.6.4 Integrated into Air Handling Unit Mixing Boxes .................................................................. 20 3.0 PERFORMANCE OBJECTIVES .................................................................................................. 22 3.1 IMPROVE COMFORT PROVIDED BY EVAPORATIVE COOLING ....................................... 23 3.2 PROVIDE HIGH-EFFICIENCY COOLING ................................................................................ 23 3.3 SUSTAIN HIGH COOLING PERFORMANCE ........................................................................... 24 3.4 MINIMIZE WATER CONSUMPTION ........................................................................................ 24 3.5 MAINTAINABILITY ................................................................................................................... 24 4.0 FACILITY/SITE DESCRIPTION ................................................................................................. 25 4.1 FACILITY/SITE LOCATION AND OPERATIONS ................................................................... 26 4.1.1 Training Facility ..................................................................................................................
Load more

Recommended publications
  • Investigating Applicability of Evaporative Cooling Systems for Thermal Comfort of Poultry Birds in Pakistan
    applied sciences Article Investigating Applicability of Evaporative Cooling Systems for Thermal Comfort of Poultry Birds in Pakistan Hafiz M. U. Raza 1, Hadeed Ashraf 1, Khawar Shahzad 1, Muhammad Sultan 1,* , Takahiko Miyazaki 2,3, Muhammad Usman 4,* , Redmond R. Shamshiri 5 , Yuguang Zhou 6 and Riaz Ahmad 6 1 Department of Agricultural Engineering, Bahauddin Zakariya University, Bosan Road, Multan 60800, Pakistan; [email protected] (H.M.U.R.); [email protected] (H.A.); [email protected] (K.S.) 2 Faculty of Engineering Sciences, Kyushu University, Kasuga-koen 6-1, Kasuga-shi, Fukuoka 816-8580, Japan; [email protected] 3 International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan 4 Institute for Water Resources and Water Supply, Hamburg University of Technology, Am Schwarzenberg-Campus 3, 20173 Hamburg, Germany 5 Leibniz Institute for Agricultural Engineering and Bioeconomy, Max-Eyth-Allee 100, 14469 Potsdam-Bornim, Germany; [email protected] 6 Bioenergy and Environment Science & Technology Laboratory, College of Engineering, China Agricultural University, Beijing 100083, China; [email protected] (Y.Z.); [email protected] (R.A.) * Correspondence: [email protected] (M.S.); [email protected] (M.U.); Tel.: +92-333-610-8888 (M.S.); Fax: +92-61-9210298 (M.S.) Received: 4 June 2020; Accepted: 24 June 2020; Published: 28 June 2020 Abstract: In the 21st century, the poultry sector is a vital concern for the developing economies including Pakistan. The summer conditions of the city of Multan (Pakistan) are not comfortable for poultry birds.
    [Show full text]
  • Thermal Science Cooling Tower Performance Vs. Relative Humidity
    thermal science Cooling Tower Performance vs. Relative Humidity BASIC THEORY AND PRACTICE Total Heat Exchange A mechanical draft cooling tower is a specialized heat exchanger G = mass rate of dry air [lb/min] in which two fluids (air and water) are in direct contact with each L = mass rate of circulating water [lb/min] other to induce the transfer of heat. Le = mass rate of evaporated water [lb/min] THW = temperature of hot water entering tower [°F] Ignoring any negligible amount of sensible heat exchange that TCW = temperature of cold water leaving tower [°F] hin = enthalpy of air entering [Btu/lb/dry air] may occur through the walls (casing) of the cooling tower, the heat hout = enthalpy of air leaving [Btu/lb/dry air] gained by the air must equal the heat lost by the water. This is Cp = specific heat of water = 4.18 [Btu/lb-°F] an enthalpy driven process. Enthalpy is the internal energy plus Win = humidity ratio of air entering [lb water/lb dry air] the product of pressure and volume. When a process occurs at Wout = humidity ratio of air leaving [lb water/lb dry air] constant pressure (atmospheric for cooling towers), the heat In order to know how much heat the air flowing through a cooling absorbed in the air is directly correlated to the change in enthalpy. tower can absorb, the enthalpy of the air entering the tower must This is shown in Equation 1. be known. This is shown on the psychrometric chart Figure 1. G (hout - hin) = L x Cp (THW - 32°) - Cp (L - Le)(TCW - 32°) (1) The lines of constant enthalpy are close to parallel to the lines of constant wet bulb.
    [Show full text]
  • Recommended Qualification Test Procedure for Solar Absorber.Pdf
    Date: 2004-09-10 Editor Bo Carlsson1 IEA Solar Heating and Cooling Program Task 27 Performance of Solar Façade Components Project: Service life prediction tools for Solar Collectors Recommended qualification test procedure for solar absorber surface durability 1 Address: SP Swedish National Testing and Research Institute, P.O.Box 857, SE-50115 Borås, e-mail: [email protected] Contents Page Foreword.............................................................................................................................................................iv Introduktion .........................................................................................................................................................v 1 Scope ......................................................................................................................................................1 2 Normative references ............................................................................................................................1 3 Terms and definitions ...........................................................................................................................2 4 Requirements and classification..........................................................................................................3 5 Test methods for assessing material properties as measure of absorber performance...............4 5.1 Sampling and preparation of test specimens.....................................................................................4
    [Show full text]
  • Evaluation of the Effect of Relative Humidity of Air on the Coefficients of Critical Flow Venturi Nozzles
    Evaluation of the Effect of Relative Humidity of Air on the Coefficients of Critical Flow Venturi Nozzles K. Chahine and M. Ballico National Measurement Institute, Australia P O Box 264, Lindfield, NSW 2070, Australia [email protected] Abstract atmospheric pressures. To establish stable sonic conditions in the nozzle, the down-stream end of the nozzle is usually connected to a high-capacity vacuum At NMIA, volumetric standards such as Brooks pump, with the up-stream end connected to the meter- or bell provers are used to calibrate critical flow Venturi under-test. During calibration the test-flowmeter draws nozzles or “sonic nozzles”. These nozzles, which are air from the laboratory at or near atmospheric pressures extremely stable, are used by both NMIA and Australian and temperature, and with relative humidity varying accredited laboratories to establish continuous flows for between 40% and 60%. The mass flowrate produced by the calibration of gas flow meters. For operational the nozzles is calculated based on the calibrated values of reasons, sonic nozzles are generally calibrated using dry the nozzle coefficient, the measured up-stream pressure air but later used with standard atmospheric air at various and the density calculated from the air temperature, humidity levels either drawn or blown through the meter- pressure and humidity [2]. under-test. Although the accepted theoretical calculations for determining the mass flow through a sonic nozzle At present, any effect of the relative humidity on the incorporate corrections for the resulting change in air nozzle coefficients is considered as negligible, as various density, as laboratories seek to reduce uncertainties the authors have estimated the systematic error at 0.02% for validity of this assumption warrants further examination.
    [Show full text]
  • Psychrometrics Outline
    Psychrometrics Outline • What is psychrometrics? • Psychrometrics in daily life and food industry • Psychrometric chart – Dry bulb temperature, wet bulb temperature, absolute humidity, relative humidity, specific volume, enthalpy – Dew point temperature • Mixing two streams of air • Heating of air and using it to dry a product 2 Psychrometrics • Psychrometrics is the study of properties of mixtures of air and water vapor • Water vapor – Superheated steam (unsaturated steam) at low pressure – Superheated steam tables are on page 817 of textbook – Properties of dry air are on page 818 of textbook – Psychrometric charts are on page 819 & 820 of textbook • What are these properties of interest and why do we need to know these properties? 3 Psychrometrics in Daily Life • Sea breeze and land breeze – When and why do we get them? • How do thunderstorms, hurricanes, and tornadoes form? • What are dew, fog, mist, and frost and when do they form? • When and why does the windshield of a car fog up? – How do you de-fog it? Is it better to blow hot air or cold air? Why? • Why do you feel dry in a heated room? – Is the moisture content of hot air lower than that of cold air? • How does a fan provide relief from sweating? • How does an air conditioner provide relief from sweating? • When does a soda can “sweat”? • When and why do we “see” our breath? • Do sailboats perform better at high or low relative humidity? Key factors: Temperature, Pressure, and Moisture Content of Air 4 Do Sailboats Perform Better at low or High RH? • Does dry air or moist air provide more thrust against the sail? • Which is denser – humid air or dry air? – Avogadro’s law: At the same temperature and pressure, the no.
    [Show full text]
  • Model 1830, 1850 & 1850W Dehumidifier Owner's Manual
    Model 1830, 1850 & 1850W Dehumidifier Owner’s Manual PLEASE LEAVE THIS MANUAL WITH THE HOMEOWNER Installed by: _________________________________ Installer Phone: _______________________ Date Installed: _______________ ON/OFF button Up/Down Dehumidifer Control Outlet used to turn buttons used to dehumidifier on change humidity and off setting MODE button used for optional ventilation feature Inlet Filter Access Drain Power Door Switch 90-1874 WHOLE HOME Dehumidification The Aprilaire® Dehumidifier controls the humidity level in your entire home. A powerful blower inside the dehumidifier draws air into the cabinet, filters the air and removes moisture, then discharges the dry air into the HVAC system or dedicated area of the home. Inside the cabinet, a sealed refrigeration system removes moisture by moving the air through a series of tubes and fins that are kept colder than the dew point of the incoming air. The dew point is the temperature at which moisture in the air will condense, much like what occurs on the outside of a cold glass on a hot summer day. The condensed moisture drips into the dehumidifier drain pan to a drain tube routed to the nearest floor drain or condensate pump. After the moisture is removed, the air moves through a second coil where it is reheated before being sent back into the home. The air leaving the dehumidifier will be warmer and drier than the air entering the dehumidifier. SETTING THE DESIRED HUMIDITY LEVEL The dehumidifier on-board control will display the humidity setting when not running, and ENERGY SavinGS TIPS displays the measured humidity when running. Energy Savings Tip #1: Adjust the humidity setting to be as high as is comfortable to reduce dehumidifier run time.
    [Show full text]
  • Factors Affecting Indoor Air Quality
    Factors Affecting Indoor Air Quality The indoor environment in any building the categories that follow. The examples is a result of the interaction between the given for each category are not intended to site, climate, building system (original be a complete list. 2 design and later modifications in the Sources Outside Building structure and mechanical systems), con- struction techniques, contaminant sources Contaminated outdoor air (building materials and furnishings, n pollen, dust, fungal spores moisture, processes and activities within the n industrial pollutants building, and outdoor sources), and n general vehicle exhaust building occupants. Emissions from nearby sources The following four elements are involved n exhaust from vehicles on nearby roads Four elements— in the development of indoor air quality or in parking lots, or garages sources, the HVAC n loading docks problems: system, pollutant n odors from dumpsters Source: there is a source of contamination pathways, and or discomfort indoors, outdoors, or within n re-entrained (drawn back into the occupants—are the mechanical systems of the building. building) exhaust from the building itself or from neighboring buildings involved in the HVAC: the HVAC system is not able to n unsanitary debris near the outdoor air development of IAQ control existing air contaminants and ensure intake thermal comfort (temperature and humidity problems. conditions that are comfortable for most Soil gas occupants). n radon n leakage from underground fuel tanks Pathways: one or more pollutant pathways n contaminants from previous uses of the connect the pollutant source to the occu- site (e.g., landfills) pants and a driving force exists to move n pesticides pollutants along the pathway(s).
    [Show full text]
  • Indoor Air Quality in Commercial and Institutional Buildings
    Indoor Air Quality in Commercial and Institutional Buildings OSHA 3430-04 2011 Occupational Safety and Health Act of 1970 “To assure safe and healthful working conditions for working men and women; by authorizing enforcement of the standards developed under the Act; by assisting and encouraging the States in their efforts to assure safe and healthful working conditions; by providing for research, information, education, and training in the field of occupational safety and health.” This publication provides a general overview of a particular standards-related topic. This publication does not alter or determine compliance responsibili- ties which are set forth in OSHA standards, and the Occupational Safety and Health Act of 1970. More- over, because interpretations and enforcement poli- cy may change over time, for additional guidance on OSHA compliance requirements, the reader should consult current administrative interpretations and decisions by the Occupational Safety and Health Review Commission and the courts. Material contained in this publication is in the public domain and may be reproduced, fully or partially, without permission. Source credit is requested but not required. This information will be made available to sensory- impaired individuals upon request. Voice phone: (202) 693-1999; teletypewriter (TTY) number: 1-877- 889-5627. Indoor Air Quality in Commercial and Institutional Buildings Occupational Safety and Health Administration U.S. Department of Labor OSHA 3430-04 2011 The guidance is advisory in nature and informational in content. It is not a standard or regulation, and it neither creates new legal obligations nor alters existing obligations created by OSHA standards or the Occupational Safety and Health Act.
    [Show full text]
  • Temperature & Humidity Control in Surgery Rooms
    This article was published in ASHRAE Journal, June 2006. Copyright 2006 ASHRAE. Posted at www.ashrae.org. This article may not be copied and/or distributed electronically or in paper form without permission of ASHRAE. For more information about ASHRAE Journal, visit www.ashrae.org. Health-Care HVAC Temperature & Humidity Control In Surgery Rooms By John Murphy, Member ASHRAE requirements. This analysis focuses on cooling and dehumidification; heating ccupant comfort, infection control, and drying of mucous and humidification are not addressed. coating are some reasons why temperature and humidity Impact on HVAC System Design O The temperature and humidity control control are important in surgery rooms.1 Temperature and humid- requirements for a surgery room, along with the high air change rate, significantly ity ranges, and minimum air-change rates often are prescribed by impact the design of the HVAC system. Using a rule of thumb (such as 400 local codes or by industry-accepted guidelines (Table 1). cfm/ton [54 L/s per kW]) or a traditional temperature-only design approach often Surgeons also have preferences when in Farmington, Maine, said, “We always leads to a system that is unable to meet it comes to temperature and humidity had problems being able to satisfy the requirements. conditions. Reasons for these prefer- surgeons, who wanted the temperature at The American Institute of Architects ences range from personal comfort while 62°F to 65°F (17°C to 18°C), while the (AIA) design guidelines2 recommend 15 dressed in heavy surgery clothing to the anesthesiologists and other staff wanted air changes per hour (ACH) of supply air perception of superior procedure success higher temperatures.” 4 for a surgery room, and 20% of that sup- rates.
    [Show full text]
  • GUIDE to INSULATING CHILLED WATER PIPING SYSTEMS with MINERAL FIBER PIPE INSULATION 33°F to 60°F (0.5°C to 15.6°C)
    GUIDE TO INSULATING CHILLED WATER PIPING SYSTEMS WITH MINERAL FIBER PIPE INSULATION 33°F to 60°F (0.5°C to 15.6°C) First Edition Copyright ©2015 NAIMA, ALL RIGHTS RESERVED GUIDE TO INSULATING CHILLED WATER PIPING SYSTEMS WITH MINERAL FIBER PIPE INSULATION 33°F to 60°F (0.5°C to 15.6°C) First Edition, 2015 Guide to Insulating Chilled Water Systems First Edition, 2015 CONTENTS PREFACE APPENDIX A-1 I Mineral Fiber Pipe Insulation . ii I Information Sources and References . A-2 I Vapor Retarder Jacketing Systems . ii I ASHRAE - American Society of Heating, Refrigerating, I Mineral Fiber Pipe Insulation Standards . ii and Air-Conditioning Engineers, Inc. A-2 I How This Guide Was Developed . ii i I ASTM - American Society for Testing and Materials . A-2 I ICC - International Code Council, Inc. A-2 SECTION 1: PERFORMANCE CRITERIA 1-1 I The National Research Council (NRC) . A-2 I I Role of Pipe Insulation . 1-2 NAIMA - North American Insulation Manufacturers Association . A-2 I Role of Pipe Insulation for Chilled Water Systems I 33°F to 60°F (0.5°C to 15.6°C) . 1-2 NFPA - National Fire Protection Association . A-2 I I General Requirements for Mineral Fiber Pipe National Institute of Building Sciences . A-2 Insulation in Chilled Water Applications . 1-2 I National Insulation Association . A-2 I Thermal Conductivity . 1-2 I ASHRAE Standard 90.1 Minimum Pipe Insulation I Standard Specification for Mineral Fiber Pipe Thickness Recommendations . A-3 Insulations (ASTM C547) . 1-3 I IECC Minimum Pipe Insulation Thickness I Specifications, Performance & Test Standards Recommendations .
    [Show full text]
  • Modified Version of High Efficiency Dehumidification System (HEDS) ESTCP Presentation EW-201344
    FEDERAL UTILITY PARTNERSHIP WORKING GROUP SEMINAR November 3-4, 2015 Houston, TX Modified Version of High Efficiency Dehumidification System (HEDS) ESTCP Presentation EW-201344 Hosted by: Original Presentation by: Dahtzen Chu U.S. Army Construction Engineering Research Laboratory Scot Duncan, PE, Retrofit Originality, Inc. Omar Chamma, Trane What We’ll Discuss • This presentation will discuss several different methods that are currently utilized for Relative Humidity (RH) control in DoD facilities and some of their comparative strengths and weaknesses. • The main focus of the discussion will be on the “High Efficiency Dehumidification System” or “HEDS” that is in the process of undergoing testing thru the ESTCP process. • The appendices contain FAQ’s and Psychrometric charts for typical reheat and recuperative designs. Federal Utility Partnership Working Group November 3-4, 2015 Houston, TX Comparative Baselines at DoD and Nationally Baseline for the demonstrated technology comes in several variations. 1. Simplest and most widespread comparative baseline system consists of an AHU with a chilled water or DX refrigerant sourced cooling coil that cools the air down to between 52F and 55F. 1. Removes moisture from the air via condensation, then utilizes a heating coil, either sourced by hot water or an electric reheat coil to raise the supply air temperature to lower the Relative Humidity of the air entering the spaces, drying the spaces out. 2. AHU’s equipped with Run Around coils for reheat duty in various configurations: 1. Upstream of main Cooling Coil (CC) to downstream of main CC, 2. Exhaust air to Supply air, (does not reduce plant energy in this configuration) 3.
    [Show full text]
  • With Chilled Water Systems Get Precise Cooling and Control for Research and Institutional Greenhouse Growing with Chilled Water Cooling Systems
    Control Cooling with Chilled Water Systems Get precise cooling and control for research and institutional greenhouse growing with chilled water cooling systems. Researchers and institutional greenhouse growers need precision, efficiency and reliability in cooling and control. Because this type of growing demands tightly controlled environments, many institutions turn to chilled water cooling. How Greenhouse Chilled Water vs. Cooling Works Evaporative Cooling Hydronics uses water as the heat-transfer medium in Many commercial greenhouses rely on evaporative cooling heating and cooling systems. Large-scale commercial and to cool air to about 10 to 20 degrees below the outside institutional buildings may include both a chilled and heated temperature. These systems lower air temperature using water loop for heating and air conditioning. While boilers mists, sprays, or wetted pads, because they introduce heat the water, chillers and cooling towers are often used water into ventilation air – increasing the relative humidity separately or together to cool the water. while lowering the air temperature. Chilled water cooling is a hydronic process that circulates While this is generally an efficient process, evaporative cooling chilled water through a loop piping system. Circulator is limited by the relative humidity of the outside air introduced pumps force the water through a heat exchanger, and a fan into the greenhouse. Under these conditions, evaporative draws warm air out and cools it as it passes over cold coils. cooling cannot provide effective space temperature control of the greenhouse under all operating conditions. Flexibility and Controlled Climate Growing The Delta T Solutions’ chilled water system uses hydronic cooling to precisely control greenhouse space temperature For flexibility, a chilled water system can be broken up into and humidity.
    [Show full text]