Research
Current Research
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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.
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.
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ASHRAE RP-1282 Lighting Heat Gain Distribution in Buildings |
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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 |
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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
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| 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 |
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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 |
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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
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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 |
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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) |
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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.
