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Current Research

Previous Research


Current Research


·        Advancement of DOE's EnergyPlus Building Energy Simulation Program (Sponsor: DOE-FSEC)

Oklahoma State University works as a member of the development team on the EnergyPlus building simulation program.  Detailed information about EnergyPlus can be found on www.energyplus.gov. OSU works to assist users of the program as well as enhancing simulation capabilities, and developing/implementing/testing new models based mostly around primary plant simulation and equipment.  Project duration: April 2006 - Present


Design and construction of a new psychrometric research test facility at Oklahoma State University (Sponsor: AAON Inc.)


The low temperature psychrometric chamber artificially reproduces the temperature and relative humidity of various climates around the world, from tropical to continental, from dry desert to northern and polar tundra. The temperature can range from -40 to +130°F (-40 to 55°C) and the relative humidity from 10 to 95% R.H.











This psychrometric chamber is used to experimentally study the behavior of systems and components under specific ambient conditions.  Primarily intended for testing heat pumps, refrigeration systems, and unitary equipment up to 20 tons (70 kW) of refrigerating capacity, the facility consists of two similar-size adjacent rooms of about 19 by 20 by 18 feet high. The large floor area can accommodate multiple set ups inside each room. A double panel sliding door (shown in figure here) is located next to a gantry crane, which is used to position the testing equipment inside the chamber. Project Duration: May 2007 - Present




Foundation Heat Exchanger Model and Design Tool- Development and Validation        (Sponsor: ORNL/DOE)

Can very energy efficient houses be heated and cooled by a ground-source heat pump with ground heat exchangers placed only in the foundation excavation?  Though this has been experimentally successful in a few test houses, the combination of house design, weather conditions and ground properties that allow such a low-cost ground heat exchanger design are unknown.  The goal of this project is to develop design procedures, simulation methodologies and software that facilitate design of such systems.  For cases where the ground heat exchanger solely in the foundation excavation is not sufficient, we are also looking at additional heat sinks/sources that can be used as part of a residential hybrid ground-source heat pump system.

This figure shows preliminary results from a simulation of a ground heat exchanger with six HDPE tubes.  The left-hand side of the plot is the foundation wall; the top of the plot is the ground surface. Project Duration: September 2008 - Present

Methodology to Measure Thermal Performance of Pipe Insulation at Below-Ambient Temperatures (Sponsor: ASHRAE)

Insulation systems applied to cold piping for refrigeration and de-humidification systems aim to prevent water vapor condensation on the pipe exterior surface. When a chilled fluid pipe is inadequately insulated, such condensation might occur and water drip onto the building surfaces possibly causing mold growth. In addition, moisture ingress into piping and tubing insulation can lead to degrading service life and performance of the insulation systems, corrosion of pipelines, and mold growth on the surface of the insulation.

In this project, the low temperature psychrometric chamber at Oklahoma State University is used to demonstrate a new test methodology for measuring the effective thermal conductivity of pipe insulation systems when these systems are exposed to dry and wet ambient conditions similar to the ones of field service in chilled water, refrigeration, and liquefied gas transport applications. The outcomes are used for updating the information regarding mechanical system insulation design and for building a new experimental apparatus for pipe insulation product testing.   project duration: August 2008 - Present


Waterside Fouling Performance of Brazed-Plate Type Condensers in Cooling Tower Applications (Sponsor: ASHRAE)


The water fouling test facility is designed to experimentally measure the heat transfer rate and hydraulic performance of plate heat exchangers (PHEs) under fouling conditions. The current set up replicates similar operating conditions as in the actual field of service. A variable-speed pump circulates refrigerant inside the testing PHEs. Refrigerant condenses at the ARI conditions of 105 to 110°F Saturated Condensing Temperature, 85°F Entering Water Temperature, and water flow of 3.0 GPM/ton.  The overall heating capacity is up to 37,000 Btu/hr (11 kW).

The water fouling facility is currently used to determine the fouling resistance of water cooled brazed PHEs by using simulated cooling tower water. The simulated cooling tower water is prepared in a batch inside the conical tank shown in the figure.  Water is then pumped through a series of pipelines into the plate heat exchangers and it is possible to develop correlations of fouling resistance and pressure drop with the water quality. Project duration: May 2008 - Present


Microchannel Coils in Compact Heat Pump Systems (Sponsor: OCAST) 

This project focuses on the development of a new microchannel heat exchanger that can be used as the outdoor coil in compact heat pump systems for residential and commercial applications. The work, sponsored by the Oklahoma Center for Advancement of Science and Technology (OCAST), aims to advance the technology of microchannel heat exchangers and address the main challenges that arise when these heat exchangers are used as outdoor evaporator coils in R22 and R410A systems. Both modeling and experimental efforts will provide the basic research required to address three significant problems related to the adoption of microchannel heat exchangers: (1) refrigerant maldistribution inside the heat exchangers; (2) water condensate buildup on the coils, and (3) frost buildup leading to long defrost cycles. Project Duration: Sept 2007 – present.



Effects of Fin Design on Frost and Defrost Thermal Performances of Microchannel Heat Exchangers (Sponsor: ASHRAE)

During frosting conditions an overall heat transfer coefficient is often employed for the design and analysis of these coils due to the difficulty of separating the air-side behavior from the refrigerant-side characteristics. Previous studies showed that the outside convective thermal resistance contributes 37 to 52% of the overall thermal resistance in dry coil (initial conditions). Frost accumulation on the heat transfer area of the microchannel evaporator coils penalizes further the air-side heat transfer.

This project aims to study the effect of fin design modifications on frost and defrost thermal performance of folded fin microchannel heat exchangers. Transients case of initial frost accumulation, defrost, and subsequent re-frost cycles are going to be experimentally investigated in our air flow frosting wind tunnel. Project Duration: Sept 2009 – present.



Development of Design Tools for Surface Water Heat Pump Systems (Sponsor: ASHRAE, 1385-RP) 

The objective of this project is to provide improved design data and design tools for SWHP systems.  The scope includes collection, interpretation, and collation of design data; experimental measurement of convection coefficients on submerged heat exchangers, and development of design tools. Project Duration: Sept 2009 – present. 

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Previous Research

Development of Safe Building Technologies

Building HVAC systems are a leading candidate for the deployment of emerging chemical and biological sensors. The current generation of HVAC equipment, however, has not been designed for containment or mitigation of the contaminants resulting from a chemical or biological attack.  Plans are underway to integrate the ongoing development of HVAC simulation technologies at OSU with enhanced building automation and security hardware.  The Continuous Air Quality Monitoring Laboratory for secure building systems will figure prominently in the development of the next generation of HVAC automation and security systems.  It will be used to develop simulation models, system response protocols and HVAC components for the next generation of secure building systems. 


ASHRAE RP-1282 Lighting Heat Gain Distribution in Buildings
The energy dissipated by lights is a significant contributor to the space heat gain and the space cooling load in many commercial buildings.  To account for the heat gain due to lights, both of ASHRAE's new cooling load calculation procedures require two lighting heat gain parameters, the conditioned space/ceiling plenum split and the radiative/convective split, as input data.  However, existing data are limited and may be obsolete due to recent advancements in lighting technologies.  The current project addresses the need to provide relevant lighting heat gain parameters for a range of common luminaires.  The primary objective of the study is therefore to accurately measure these lighting heat gain parameters under realistic operating conditions in a full-scale experimental room.  An additional objective is to provide the experimental results in a format that can be readily applied to the ASHRAE cooling load procedures.











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Optimal A/C cycles for 21st Century Refrigerants
This project consists of a joint effort between the York Advanced Technology Group and the Building Environmental and Thermal Systems Research Group (BETSRG) in the Department of Mechanical and Aerospace Engineering at Oklahoma State University. The two groups bring complementary expertise and resources to the project and will work closely together in a synergistic research environment to develop innovative unitary air conditioning equipment that uses advanced and natural refrigerants.

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Simulation of Ground Source Heat Pump Systems
For several years, we have been developing models for ground loop heat exchangers, heat pumps, and other related components. These models are aimed at being used in component-based modular simulation environments such as TRNSYS or HVACSIM+.

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The Geothermal Smart Bridge
Research into the geothermal smart bridge is ongoing at Oklahoma State University, with the close cooperation of the Oklahoma Department of Transportation. The project is aimed at the development of a bridge deck heating system to eliminate preferential icing.

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Standing Column Well Design and Modeling
Standing column wells are used for direct (i.e. open-loop) heat exchange with the earth. The objectives of this project include studying the characteristics of standing column wells for the purposes of establishing firm guidelines for their siting and design; developing analysis tools to strengthen these guidelines and to provide the basis for computer codes which can supply ready prediction of required well depth; and outline field tests which can provide monitoring data to verify the codes. 


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Experimental Validation of the Heat Balance and Radiant Time Series Cooling Load Calculation Procedures  ASHRAE 1117-RP
Two full scale test cells will experimentally determine room heat extraction rates under various environmental and operating conditions.  The measured sensible cooling load will be compared to the load predicted by heat balance and RTS calculation procedures. 


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Development of a Modular, Loop-Based, HVAC System Simulation
The EnergyPlus HVAC simulation environment is under developed as a hybrid implementation of component based and system based environments.  A ‘fluid loop‘, which is an abstract representation of a piping or duct system, will provide the structural framework characteristic of system based models. 


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In Situ Measurement of Ground Thermal Properties
Determination of the ground's thermal conductivity is a significant challenge facing designers of Ground Source Heat Pump (GSHP) systems applied in commercial buildings. The number of boreholes and the depth and cost of each borehole are highly dependent on the ground thermal properties.

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Evaluation of the Effects of Groundwater Flow on Closed Loop Ground Source Heat Pump Systems
Aquifer flows are widely thought to have a beneficial effect on closed loop ground source heat pump systems. However, there has been little, if any work done to quantify the effects of the groundwater flow.

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Energy Analysis of the Williams Center
The Bank of Oklahoma Tower, part of the Williams Center, a 52 story multipurpose building located in downtown Tulsa, Oklahoma. The goal of this project is to investigate system modifications that would be economically feasible and result in lower energy costs.

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Development of an Analytical Verification Test Suite for Whole Building Energy Simulation Programs - Building Fabric ASHRAE 1052-RP
This project involves the development of an analytical test suite, covering a variety of heat transfer mechanisms, for use in validating building simulation programs.

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Development of a Two-Dimensional Transient Model of Snow-Melting Systems, and Use of the Model for Analysis of Design Alternatives ASHRAE 1090-RP
The objective of this project was to develop a 2-D transient model of a snow-melting system; develop a library of storms; use the model with both steady-state data and actual storms to perform a parametric analysis of heat input requirements for various configurations, weather conditions, and free area ratios.

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Comparison of Cooling Load Calculation Methods (ASHRAE 942-RP)
This project was the first joint CIBSE-ASHRAE research project. The objective was to study the differences between current UK and US cooling load calculation methods.


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Cold Air Distribution in a Factory Built Home
Over the last three decades development of energy conservation measures for residential buildings have focused on measures that have been most applicable to colder climates where heating requirements dominate the residential energy budget. These measures while generally beneficial, do not address some of the energy related building and system design issues important in the varied climates of Oklahoma. 

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