Tools & Apparatuses
Rotatable Guarded Hot Box
The rotatable guarded hot box measures heat flux across large-scale wall/fenestration assemblies. It accommodates systems as large as 4×3 m (13×10 ft) and as thick as 0.6 m (2 ft). Chambers on both sides can maintain a range of temperatures; low-side (39 to 140°F, 4 to 60°C) and high-side (75 to 140°F, 24 to 60°C). Using this Hot Box, it is possible to expedite the conduction of accurate thermal experiments with a minimum of human interaction.
Large-Scale Climate Simulator
The large-scale climate simulator tests low-slope roof or roof/attic assemblies weighing up to 9000 kg (10 tons) and with footprints as large as 3.8×3.8 m (12.5×12.5 ft) under any inhabited climatic condition in North America. The up- per (outdoor) chamber can expose assemblies to a broad range of temperatures (−40 to 150°F, −40 to 65°C), and humidity, sunlight, and wind can also be simulated. The lower (indoor) chamber can control temperature and humidity within ranges typical for indoor conditions. Realistic static air pressure differences between the upper and lower chambers can also be maintained to simulate air leakage. The LSCS primarily measures heat flux between indoors and outdoors but also captures a wide range of secondary metrics.
Roof Thermal Research Apparatus
The roof thermal research apparatus measures effects of long-term natural weather exposure on small, low-slope roof specimens. The interior is heated and cooled to constant typical indoor conditions and houses a continuous data acquisition system. The apparatus handles up to four instrumented 1.2×2.4 m (4×8 ft) test specimens. The roof thermal research apparatus wall panels and foundation slab edges are used to evaluate wall- and slab-insulation systems under long-term weather exposure.
Hygrothermal Material Properties Laboratory
ORNL is developing hygrothermal models of building envelope assemblies and validating them against experimental data to advance understanding of heat, air, and moisture ow and how moisture accumulates in building components. Properties necessary for hygrothermal modeling are not readily available for construction materials, so facilities are available for measuring water vapor permeance, sorption and desorption isotherms, and liquid diffusivity.
A duct blaster measures air flow in a duct system and helps locate air leaks. It typically connects to the duct system at an air return while other grills are temporarily sealed. As it exerts a standard test pressure on the duct system, air ow and pressure gauges measure air leakage. ORNL’s Minneapolis Blower Door Company Duct Blaster provides air ow rates up to 1350 cfm and sustained pressures up to 50 Pa. It can be used for testing in most residential and light commercial buildings.
Insulation and Air Barrier Materials Laboratory
ORNL supports industry collaborations to develop advanced insulation and air barrier systems and testing methods. The insulation and air barrier materials laboratory enables precise measurements of properties using tools such as a heat flux meter apparatus, air ow meters, precision slicers to prepare thin slices of foam insulation for accelerated aging experiments, 13 temperature-controlled chambers for long- term aging, and air-tight chambers for aging in various gases to estimate air permeance. The heat flux meter apparatus accommodates specimens of up to 60×60×20 cm (24×24×8 in).
Three infrared cameras are available for nondestructive thermograpic imaging of building envelopes and equipment. The FLIR ThermacamTM S65 HS has a spectral range of 7.5 to 13 μm and accuracy of ±2°C (±3.6°F) or 2% of reading. Its measurement range is −40 to 1500°C (−40 to 2732°F) and operating temperature range is −15 to 50°C (5 to 122°F). Two older models, the FLIR PM 280 and PM 295, have spectral ranges of 3.4 to 5 μm and 7.6 to 13.5 μm and measurement temperature ranges of −10 to 450°C (14 to 842°F) and −40 to 500°C (−40 to 932°F), respectively.
Blower Door Apparatus
A blower door consists of a calibrated fan temporarily sealed into an exterior doorway. It forces air through gaps in the building envelope to measure envelope airtightness and locate air leaks. ORNL’s Minneapolis Blower Door Company model 3/110V is capable of air ow rates up to 6000 cfm in free air and 4900 cfm at 75 Pa of building interior pressure. Attachment ow rings allow measurements as low as 12 cfm. It can be used for testing in most residential and light commercial buildings.
Small Compressor Calorimeter Test Stand
The small compressor calorimeter test stand experimentally generates compressor performance maps for fractional-ton compressors (300 to 3600 Btu/h) used in refrigerators and other small appliances and equipment. It is equipped to safely test compressors using alternative refrigerants with some level of flammability (e.g., isobutene, propane) and non-flammable refrigerants such as hydrofluorocarbons (HFCs) and low-global warming potential (GWP) hydrofluoroolefin alternatives.
Natural Exposure Test Facilities
ORNL’s natural exposure test facilities expose side-by-side roof/attic and wall assemblies to natural weathering in four different humid US climates. The data gathered at these facilities assists industry in developing products that make envelopes more energy efficient yet avoid adverse moisture- related impacts, and are essential in validating hygrothermal and energy models. Natural exposure test structures are located at ORNL and at Charleston, SC; Tacoma, WA; and Syracuse, NY. Each is temperature and humidity controlled and instrumented to measure parameters such as moisture content in materials, vapor pressure, temperature, heat flux, humidity, and condensation.
A portable solar spectrum reflectometer is used to measure the total hemispherical solar
reflectance of exterior surfaces of building envelopes. The device uses a tungsten halogen lamp to diffusely illuminate a sample. Four detectors, each fitted with differently colored filters, measure reflected light in different wavelength ranges. The four signals are weighted in appropriate proportions to yield the total hemispherical solar reflectance.
A portable emissometer measures the total hemispherical emissivity of building envelope surfaces. Its thermopile radiation detector is heated to 82.2°C (180°F). The detector has two high-e and two low-e elements and responds only to radiation heat transfer between itself and the sample. It must be calibrated in situ using two known standards.
Water Temperature Control Loop
This apparatus tests heat-pump–based water heating systems (e.g., heat pump water heaters and integrated heat pumps for both space conditioning and water heating) in the mid-size chambers and small appliance chamber. Supply water is provided to test systems at 4.4–43.3°C (40 to 110°F). The plant for the loop includes a 2 ton nominal capacity variable-speed refrigeration system and an 18 kW electric resistance immersion heater for precise water temperature control.
Large Compressor Calorimeter Test Stand
This apparatus experimentally generates com- pressor performance maps for
compressors of up to 3 tons (3,000 to 36,000 Btu/h) like those in air conditioners and heat pumps. It can safely test compressors at very high pressures using transcritical CO2 as the refrigerant and non-flammable refrigerants such as HFCs and low-GWP hydrofluoroolefin n alternatives.
Water Heater Accelerated Durability Test Facility
This facility tests up to 10 residential heat pump water heaters simultaneously, simulating 10 years of residential operation in 10 months, to support statistical service life estimates. Electricity and gas are supplied. Total rated input power is 50 kW; supply voltage is variable from 190 to 240 V to simulate grid voltage droop. Supply water is provided over a 4.4 to 24°C (40 to 75°F) range.
High Temperature Heat Exchanger Test Loop
This loop tests air-to-water heat exchangers (HXs) at high air-side temperatures like those encountered in recovering heat from turbine exhaust in combined heat and power applications. It features variable air ow from 10 to 1500 cfm, entering air temperatures from room temperature up to 593°C (1100°F), and entering water temperatures from 10 to 93.3°C (50 to 200°F).
Computational Fluid Dynamics
Computational fluid dynamics modeling is conducted using a 65-inch LCD screen for visualization, four work stations, computers with quad processors, and FLUENT and SolidWorks modeling packages.
Pumped Liquid Refrigerant Test Loop
This loop for testing refrigerant-to-air HXs precisely controls entering refrigerant temperature and pressure. It accommodates evaporators with capacities up to 2 tons (24,000 Btu/h) and evaporating temperatures of 4.4 to 10°C (40 to 50°F), and condensers up to 3 tons (36,000 Btu/h) and condensing temperature of 48.9°C (120°F). Alternative pure refrigerants can be tested without lubricating oil. The air-side loop moves up to 7000 cfm of air against a 4 inch (water gauge) HX pressure drop. Thermal imaging can deter- mine ow maldistribution through the HX.
Fluid Physical Properties Laboratory
This lab contains precision instruments for measuring density, viscosity, thermal conductivity, thermal diffusivity, and specific heat of fluids. They can be programmed to perform a temperature scan of a sample and measure properties over a broad temperature range while unattended. Instruments include an Anton Paar DMA 4100 M (density), an Anton Paar AMVn automated microviscometer, and a Therm-test THW (thermal conductivity and diffusivity and specific heat).
Two-Phase Flow Neutron Imaging Stand
ORNL’s High Flux Isotope Reactor uses neutron imaging to simultaneously measure refrigerant 2-phase ow void fraction, pressure drop, and heat transfer in single- and multi- channel HXs. Images and other information generated guide HX redesign (e.g., to eliminate refrigerant maldistribution). The test apparatus accommodates ow channels of various sizes and materials and operates over a range of operating conditions and with several low-GWP refrigerants. It consists of a refrigerant flow loop and a test section that allows microchannel HXs to be interchanged.
Bench Top Wind Tunnel
The Omega WT4401-D wind tunnel tests novel HX concepts and features such as n performance. It is also used to calibrate hot wire anemometers and other less precise air
flow sensors. The test chamber has a cross- section area of 10×10 cm (4×4 in.) and induces a ow rate from 25 to 9,000 cfm. It is fully instrumented with high-accuracy barometric pressure, differential pressure, temperature, and relative humidity sensors. Flow rate measurement accuracy ranges from 1 to 2%. All instruments are provided with National Institute of Standards and Technology (NIST)-traceable calibration.
Additive Manufacturing Plastic Heat Exchanger 3-Dimensional Printer
The Objet30TM 3D printer is used for rapid prototyping of functional HXs from plastics. HXs manufactured must t within a 3D envelope size of 295×190×150 mm (11.6 by 7.6 by 5.9 in.). Dimensional HX accuracy is within ± 0.1 mm (± 0.004 in.). HXs can be manufactured from different materials, but each build must be with a single material. Several build materials are available.