High Efficiency Dehumidification System (HEDS)

Transcription

1 ESTCP Deep Dive High Efficiency Dehumidification System (HEDS) EW Scot M. Duncan, P.E. Conservant Systems, Inc. August 16, 2017 Tampa Convention Center Tampa, Florida

2 Project Team ESTCP Project EW Scot Duncan, HEDS Inventor System design Project installation, commissioning and oversight. Data acquisition Dahtzen Chu, US Army CERL Principal Investigator Data analysis and reporting. Project Management Demonstration Sites Tinker AFB, OK Fort Bragg, NC 2

3 Problem Statement: Current strategies for humidity control are energy intensive and ineffective. Overcooling and reheating systems inefficient and lead to uncomfortable indoor temps and/or moisture control issues Desiccants/energy recovery wheels/run-around coils/air to air heat exchangers Other RH control methods have some or all of the following drawbacks: added complexity and equipment required, higher required maintenance skill-sets and costs, inability to modulate capacity to meet needs, need for near perfect mixed air and exhaust air filtration systems, higher fan energy requirements, higher overall energy requirements, inability to fit into existing mechanical equipment rooms for retrofit projects, significant added weight, reduced chilled water system temperature differential, leading to Low Delta T Syndrome, condensate can still get blown off of the cooling coils into the system, wet-filter syndrome for after-filters, potential for condensation and biological growth in the HX systems. Also Latent energy portion of total is increasing as building envelopes improve and internal loads decrease. Mold Costly to remediate Poses health concern especially in medical facilities Costs are not considered in energy investment calculation. 3

4 Encounters with Mold In HVAC Systems In Ductwork In Occupied spaces 4

5 Solution: High Efficiency Dehumidification System (HEDS) Conventional AHU Design Small cooling & reheat coils High CHW flow rates Low CHW temperature differential High AHU air pressure drops Propensity to suffer Low Delta T Syndrome HEDS AHU Design Very large cooling & cooling recovery coils Low CHW flow rates High CHW temperature differential/series Chiller Potential, Eliminates Low Delta T Syndrome Low AHU air pressure drops Heat recovery to replace reheat energy Reduces Infrastructure, O&M Costs 5

6 Existing Undersized Heat Transfer Coils Hurt Overall System Performance 650 HP 88 HP If you put the radiator from a Pinto into a 2017 Corvette, on a hot day, you would only have a usable 88 HP from the Corvette before it overheats. When it comes to heat transfer coils, size really does matter Your brand new Corvette high performance ESPC chiller plant can only run like a Pinto unless the AHU systems are upgraded as well. 6

7 Tech Specs Approach Temps and Temp Differentials Normal (small) HVAC AHU coiling coils are designed with a 10F to 15F air to water approach temperature. That means that the air temperature will be 10F to 15F warmer than the CHW temperature entering the cooling coil. 40F to 45F CHW supply equates to 55F supply air leaving the coil, typically using a 10F to 15F CHW system design TD, mostly operating at a 6F to 8F CHW TD when dehumidifying. HEDS coils are very large, with 2.5X to 3.5X the heat transfer surface area of a normal coil. HEDS coils are designed with a 3F to 5F air to water approach temperature. 45F CHW supply equates to 48F to 50F supply air leaving the coil. HEDS CHW TD design is between 17F and 23F, can be 30F. HEDS can still dehumidify with water temps at 60F 7

8 Cooling Load Fort Bragg Cooling Load W/O HEDS (blue line) Cooling Load with HEDS (orange Line) Savings % (grey Line) 8

9 Chilled Water System Temperature Differentials Fort Bragg AHU Cooling Coil CHW TD (blue line) AHU Total Net CHW TD (orange Line) HEDS CHW 20% to 50% load is 14F to 21F. Base case ran around 3F to 7F with Low Delta T Syndrome under similar conditions From a CHW Flow Perspective, the system sees a 14F to 21F TD, from a CHW Load Perspective, the CHW System sees a 10F to 15F TD. The Difference is the Load Savings. 9

10 Demonstration Sites Tinker AFB Fort Bragg

11 HEDS Field Performance Results Application Operating Rooms, Industrial Clean Rooms Hot / Humid Climates Dining, barracks, Dedicated Outdoor Air Systems, hospital, labs, industrial clean rooms, equip coating facilities, and Corrosion Control Facilities Less Humid Environments Tested Supply Dewpoint Temperature Range (lower equals drier) AHU Cooling Load % Reduction AHU Dehumidificati on Heating Load % Reduction Estimated Total Dehumidification- Related Cooling + Heating Plant Energy Savings Less than 50 F 20% 100% 57-81% Between 50 F and 52 F Between 52 F and 56 F 31% 100% 63-85% 37% 100% 67-87% Office and Administrative Between 50 F and 56 F 27% to 29% 100% 79-91%

12 HEDS Psychrometric Chart, Fort Bragg 12

13 HEDS Psychrometric Chart, Tinker AFB 13

14 ASHRAE Addresses Dehumidification Systems Standard Where humidity controls are provided, such controls shall prevent reheating, mixing of hot and cold airstreams, or other means of simultaneous heating and cooling of the same airstream. (Section ) The system controls shall not permit reheat or any other form of simultaneous heating and cooling for humidity control. (Section 6.3.2) HEDS Can Help: Provides low first-cost option for code compliance. Code compliant system that is scalable from <100 CFM (individual barracks rooms) to >1,000,000 CFM (aircraft Corrosion Control Facilities, labs, manufacturing, clean rooms) 14

15 Lower Maintenance HEDS vs. Normal cooling/reheat AHU HEDS requires less maintenance and extends equipment lifecycles. HEDS - Boilers and hot water pumps are off all dehumidification season. HEDS - Less corrosion inside the AHU and ductwork, due to near zero water carry off from the coils. HEDS - Longer filter change intervals 200 FPM face velocity vs. over 500 FPM face velocity. HEDS - Elimination of Low Delta T Syndrome reduces extra chiller, extra CHWP, extra CDWP, extra CTF run time and extends their lifecycle. HEDS - Reduced loads and runtime reduce water and chemical treatment costs for water cooled chiller systems HEDS - Larger coils and enhanced usable chiller capacity can reduce entire HVAC system run time by over 50% in non-24/7 loads, reducing maintenance and extending HVAC lifecycle. Most potential RH control alternatives are not appropriate for most loads on most bases. Additional equipment and unfamiliar technologies increase the maintenance burdens on the bases, and also have more potential failure points. 15

16 Winner of Inaugural 2016 FEMP JUMP Call For Innovation Competition HEDS competed in and won the inaugural DoE FEMP JUMP Call For Innovation Energy Efficiency Technology competition. HEDS performance data is currently being reviewed by Oak Ridge National Laboratories. Main reason given for the HEDS win by Dr. Timothy Unruh, then Director of FEMP: The energy savings potential of HEDS is too high, no one will believe you unless you have a national lab facility verify the savings. 16

17 Reasons to Use HEDS in Hospitals At many medical facilities, there are existing situations in which the current HVAC system is not meeting the needs of their surgical teams and HVAC-caused biological growth is occurring. HEDS can help to: Solve the temperature, relative humidity control and indoor condensation problems in OR s and critical areas. Provide the lower air temperatures and lower RH s requested and required by surgical teams. Eliminate HVAC-caused biological growth problems. Save significant amounts of energy. Incorporate UltraViolet Germicidal Irradiation (UGVI) and added filtration efficiency to reduce airborne pathogens. Can allow a higher Outside Air (OA) percentage to reduce recirculated air problems, while still reducing energy consumption and chiller capacity requirements. Require reduced maintenance levels when compared to the options. Comply with ASHRAE prescriptive energy codes that do not allow simultaneous heating and cooling for RH control, unless the reheat source is reclaimed energy or renewable energy-sourced. HEDS uses reclaimed energy for RH-related reheat control. 17

18 Reasons to Use HEDS in Hospitals, continued Simplicity. There is no simpler way to provide RH control. Simplicity is resilience. Eliminates condensate blow off from the cooling coils. Eliminates after-filter wetting and biological growth on the after-filters due to condensation on the filters. The variable speed design continuously and automatically adjusts for air-filter loading, so the required Air Changes per Hour (ACH) and pressure relationships between rooms can be maintained without operator intervention. The variable speed design can allow the air change rate to be turned down by 75% when the OR s are not in use, significantly increasing the energy savings. Can help to solve chilled water plant Low Delta T Syndrome by providing load CHW system temperature differentials (TD s) of greater than 20 F. The higher chilled water system TD saves chiller plant energy and increases the energy storage capacity of Thermal Energy Storage (TES) systems. The chiller and piping capacity that is freed up by HEDS can be used elsewhere on the site. 18

19 Technology Transfer Now the Hard Part! Providing training to ESCOs such as AECOM, NORESCO, CEG, Tetra Tech, Honeywell Trane is a team member, and we will be training their teams in 2017 Future transition efforts: One possibility is the Army s Installation Technology Transition Program (ITTP) which is a conduit for demonstrating and validating new technologies. Other ESTCP demonstration projects, i.e. barracks, Navy ships, FOB s, CCF s, Hospitals, consulates, South Pacific facilities Potential DoE/DoD sponsored educational webinars on the technology. USACE could deliver the seminar or joint delivery. Figure out how to capture avoided mold prevention/ remediation costs for improved ESPC project economics. 19

20 Needs/Future Plans/Best Way to Save DoD Funds Search for ways to get more test projects installed in a variety of facility types. Developed a software Energy Efficiency evaluation tool that will allow rapid Go/No-Go decisions for application of HEDS in various locations around the globe at various facility types. Currently working with Oak Ridge National Laboratories on computer simulation tools that augment the tools that we have already developed. One of the biggest things that could be done to reduce annual DoD expenses is to allow ESPC projects ESCO s and UESC s to recognize the real and ongoing costs associated with mold remediation costs, facility quarantine and relocation costs, and the costs associated with condemned facilities due to mold growth. If these costs can be included, every project we have looked at so far, and there have been many, would have a simple payback in less than 2 years, most would be less than 1 year. 20

21 In Summary If applied broadly across the DoD and Federal portfolios, HEDS can have a meaningful, measureable impact on initial capital and ongoing operational expenditures. For new buildings, if they are to be ASHRAE 90.1 Code Compliant, HEDS can reduce construction costs. Operating costs will also be lower than typical alternatives. For retrofit applications, HEDS can reduce chiller plant and boiler plant energy consumption by 40% to 60% or more. Simplicity will rule the day to provide the lowest lifecycle costs. Please contact me with project opportunities 21

22 Contact Page Dahtzen Chu, Principal Investigator Contracting Officer's Representative U.S. Army Construction Engineering Research Laboratory Energy Branch Scot M. Duncan, P.E. President Conservant Systems, Inc