Completed Research - April 2013
Results of Completed ASHRAE Research Available
The final reports for the following research projects are available for free for ASHRAE members. Visit www.ashrae.org/research and log in to gain access. The ASHRAE Transactions papers are available for $5 for ASHRAE members at www.ashrae.org/bookstore.
In 2007 the EPA noted 1.5% of the USA’s nation’s energy load was from data centers and that energy use this could double by 2011. CFD can be a tool to optimize data center design, layout and energy efficiency. Modeling the rack is one of the critical pieces in this design but real data sets against which to compare models are rare due to the mission critical nature of these facilities. To fill this need, 1487-RP, “The Development of Simplified Rack Boundary Conditions for Numerical Data Center Models,” has developed steps to guide the CFD user in developing their own rack models for any CFD platform using input of heat dissipation rate and fan volumetric flow rate. The tool in the final report will allow designers to more quickly, confidently, and accurately model data centers. A technical paper on this project published in ASHRAE Transactions (Vol. 118 (2), SA-12-009) is available now. 1487-RP, “The Development of Simplified Rack Boundary Conditions for Numerical Data Center Models,” was sponsored by TC 4.10, Indoor Environmental Modeling. The principal investigator was Dr. John Zhai with the University of Colorado.
Pressure differential (PD) of 0.05 in. (12.5 Pa.), as a single criterion for cleanrooms, has been used for many years since adopted into Federal Standard 209 and the ASHRAE Handbook. This criterion is believed over-simplified and no longer precise for more complex conditions and applications. 1344-RP, “Cleanroom Pressurization Strategy Update – Quantification and Validation of Minimum Pressure Differentials for Basic Configuration and Applications,” presents a list of minimum PD requirements across cleanroom envelopes grouped by cleanliness class difference. Furthermore, since some auxiliary devices could contribute a possible reduction on room cleanliness requirement, ACH or PD value, a table of auxiliary device benefits is presented as well. These tables are intended to replace the existing “single” pressure differential criterion. Technical papers on this project were published in ASHRAE Transactions (Vol. 119 (1), DA-13-011, DA-13-12) are available now.
1344-RP, “Cleanroom Pressurization Strategy Update – Quantification and Validation of Minimum Pressure Differentials for Basic Configuration and Applications,” was sponsored by TC 9.11, Clean Spaces. The principal investigator was Wei Sun with Engsysco.
Brazed plate heat exchangers (BPHEs) were recently introduced for use in cooling tower applications because they can provide higher heat transfer rate per unit volume and are more compact than conventional tube-and-shell exchangers. However, users of this type of equipment have typically applied the same fouling factors recommended for tube-type heat exchangers. 1345-RP, “Waterside Fouling Performance of Brazed-Plate Type Condensers in Cooling Tower Applications,” presents a new experimental methodology and validation of waterside thermal performance of BPHE’s under fouling operating conditions. This final report presents experimentally validated fouling resistance correlations and pressure drop correlations were provided for possible inclusion in the ASHRAE Handbook and possibly the AHRI Guideline E. Technical papers on this project published in ASHRAE Transactions (Vol. 118 (1), CH-12-033) and ASHRAE HVAC&R Research Journal (Vol. 17(2), April 2011) are available now. 1345-RP, “Waterside Fouling Performance of Brazed-Plate Type Condensers in Cooling Tower Applications,” was sponsored by TC 8.5, Liquid-to-Refrigerant Heat Exchangers. The principal investigator was Dr. Lorenzo Cremaschi with the Oklahoma State University.
Many cleanrooms and bio-safety facilities utilize airlocks at each entrance and exit for personnel, material, equipment, and product traffic to minimize the flow of contaminated air between clean spaces and less-clean or unclassified corridors. Despite these airlocks being commonly employed, critical in nature, and energy and space use intensive, they’ve not been thoroughly studied. A recently completed ASHRAE project has researched the effectiveness of numerous parameters (air lock type, number of doors, pressure differential, supply air flow rate, time-delay in opening of airlock doors, walk-in vs. walk-out, door-in vs. door-out) to optimize cleanroom decontamination results, energy and space use. The method presented in the final report can lead to development of a future ASHRAE standard for airlocks. A technical paper has been submitted for future publication in ASHRAE Transactions. 1431-RP, “Analysis of Transient Characteristics, Effectiveness, and Optimization of Cleanroom Airlocks,” was sponsored by TC 9.11, Clean Spaces. The principal investigator was Mr. Wei Sun with Engsysco.
Hourly weather data files available from ASHRAE have been limited in the number of locations available outside the US and Canada. These weather files are required input for building energy simulation programs commonly used in design. However, development requires hourly measurements over a 15-30 year historical period and formatting for use in energy simulation programs. With much of the raw weather data now being much easier to track and access, 1477-URP,” Development of Typical Year Weather Files from ISH Database of Historical Weather Data for 2005 International Locations,” developed over 3,000 new international weather files included in the ASHRAE IWEC 2.0 DVD. The final report details the development of this data. Technical papers on this project published in ASHRAE Transactions (Vol. 116 (1), OR-10-045 and Vol. 115 (2), LO-09-062) are available now. 1477-URP,” Development of Typical Year Weather Files from ISH Database of Historical Weather Data for 2005 International Locations,” was sponsored by TC 4.2, Climatic Information. The principal investigator was Mr. Joe Huang with White Box Technologies.
Microchannel-type heat exchangers have been recently adopted by the heat pump industry because of their compactness and efficiency for heating and cooling in residential and commercial applications. If used in outdoor refrigerant to-air direct expansion coils, they are subjected to significant frost growth and frequent defrost cycles, which ultimately limit their heating performance during winter. 1589-URP, “Effects of Fin Design on Frost and Defrost Thermal Performances of Microchannel Heat Exchangers,” experimentally investigated the effects of surface temperature, fin geometry, fin surface coatings and air psychrometric conditions on the thermal and hydraulic performance of the microchannel heat exchangers under frosting conditions. The final report includes data and correlations that predict frost thickness, air-side face-velocity reduction, and heat transfer coefficients for louvered folded fins operating under quasi-steady state frosting conditions in microchannel-type evaporators. A technical papers on this project published in ASHRAE Transactions (Vol. 118 (1), CH-12-034) is available now. 1589-URP, “Effects of Fin Design on Frost and Defrost Thermal Performances of Microchannel Heat Exchangers,” was sponsored by TC 8.4, Air-to-Refrigerant Heat Transfer Equipment. The principal investigator was Dr. Lorenzo Cremaschi with the Oklahoma State University.
Mechanical pipe insulation systems are often installed around cold cylindrical surfaces, such as chilled water pipes, in HVAC&R applications that work at below ambient temperatures. It is crucial the insulation system work properly to prevent freezing, condensation, mold growth, even corrosion. ASTM C335 presents a methodology for measuring thermal conductivity of pipe insulation systems but it is based on a heated pipe approach with outward heat flow and does not consider water vapor movement or condensation at below ambient applications. 1356-RP, “Methodology to Measure Actual Thermal Performance of Pipe and Duct Insulation at Below-Ambient Temperature,” developed a method and experimental apparatus to measure the thermal conductivity of mechanical pipe insulation systems operating below ambient temperature. A technical paper on this project was published in ASHRAE Transactions (Vol. 118 (1), CH-12-034) and is available now.
1356-RP, “Methodology to Measure Actual Thermal Performance of Pipe and Duct Insulation at Below-Ambient Temperature,” was sponsored by TC 1.8, Mechanical Systems Insulation. The principal investigator was Dr. Lorenzo Cremaschi with Oklahoma State University.
As contemporary building designs often include large windows or glass curtain walls, modeling convective heat transfer at the interior surfaces of these windows becomes crucial in calculating loads. 1416-RP, “Development of Internal Surface Convection Correlations for Energy and Load Calculation Methods,” has investigated interior convective heat transfer at perimeter curtain walls and window surfaces with over 200 experiments. The results will allow designers to better predict interior convection and calculate loads for these architectural designs. The final report details an algorithm to estimate load based on geometrical conditions, mechanical equipment present, operating mode, and thermal conditions in the space for implementation into the ASHRAE Load Toolkit. Furthermore, correlations are formatted for inclusion into ASHRAE Handbooks chapters for use by practitioners. A technical paper was published in the ASHRAE HVAC&R Research Journal (Vol. 16(5), September 2010) and is available now. 1416-RP, “Development of Internal Surface Convection Correlations for Energy and Load Calculation Methods,” was sponsored by TC 4.7, Energy Calculations. The principal investigator was Dr. Atila Novoselac with the University of Texas-Austin.
The use of water as a refrigerant (R718) in refrigeration applications could have distinct advantages over traditional refrigerants. However, difficulties arise during manufacturing low-cost but high-performance compressor impellers to compress this natural refrigerant that still need to be addressed. 1476-URP, “Woven Compressor Enabling Economic and Scalable R718 Chillers – Phase 1: Proof of Concept,” set out to demonstrate a novel manufacturing method to manufacture composite impellers for compressing water-vapor refrigerant at a low cost. The final report demonstrates the feasibility of this manufacturing process and presents performance data that can be interpreted as a starting point upon which considerable improvements are possible. A technical paper has been submitted for future publication in ASHRAE Transactions. 1476-URP, “Woven Compressor Enabling Economic and Scalable R718 Chillers – Phase 1: Proof of Concept,” was sponsored by TC 8.2, Centrifugal Machines. The principal investigator was Dr. Norbert Mueller with Michigan State University.