BTC HVAC Research Facilities


Environmental chambersAir-to-refrigerant heat exchanger test loop
Compressor calorimetersAbsorption heat and mass transfer rigs
Multipurpose vapor
compression test loops
Corrosion test laboratory

Environmental Chambers

Heat pump testing at the BTC

A large, two room psychrometric test stand is located at ORNL in Building 3144. The test stand features both natural gas and electric utilities to support testings of thermally activated heat pumps (TAHPs), electric vapor compression heat pumps, refrigerators, desiccant heat pump systems, and fully hydronic systems. Steady-state frosting/ defrosting and cycling mode testing are successfully conducted according to ASHRAE Standards 240-89, 37-88 and 116-83. The larger room has a 15 ft 18 ft footprint, while the smaller room is 15 ft 12 ft. The refrigeration system can support 20 tons of load at an ambient temperature of 95F. The refrigeration plant can hold the ambient temperature at 20F while supporting a 3-ton load with 300 cfm of laboratory make-up air injected into the system. Relative humidity can be controlled in each room over a 50 to 90% range.

A programmable logic controller (PLC) monitors and controls all functions of the chamber's refrigeration and reconditioning plant. The PLC can be accessed off-site and allows real-time access to test data, and remote operation of the test stand.

A second two-room chamber set, located off-site at University of Tennessee facilities, is also available. Each room is 10 ft 12 ft 10 ft high. One room has a 5-ton load capacity and can simulate outdoor conditions from 10 to 125F with RH control from 50 to 90%.

A small single-room chamber measuring 8 ft 8 ft 8 ft high for appliance testing under controlled conditions is available at ORNL. It has about a 2-ton load capability and can maintain controlled temperatures in the 10 to 100F range.

Compressor Calorimeter Facilities

Two secondary refrigerant calorimeters are available at ORNL. One has a rated capacity range of 18,000 to 50,000 Btu/h and the other a range of 100 to 3000 Btu/h. A small environmental chamber (3 ft 3 ft 3 ft) is available to provide a controlled temperature space for test compressors. This chamber can control temperatures over a range of 112 to 350F.

Water-to-Water Heat Pump Test Loops

The vapor-compression refrigeration cycle test loop available at ORNL is equipped with variable-speed compressors and drives and can handle capacities of up to about 3–4 tons. The unit features a relatively low refrigerant charge requirement (approximately 5 lbs) and sample chambers located in the compressor discharge line and the liquid line. These chambers allow exposure of material samples to refrigerant/oil environments at typical operating conditions for applications ranging from low-temperature refrigeration to comfort air-conditioning (evaporating temperatures from 40 to 50F). In addition to the materials testing feature, this rig can be used to compare cycle performance of different refrigerants and refrigerant mixtures under the same operating conditions.

Heat Exchanger Test Facility (HXTF)

An air recirculation loop for testing air-to-water heat exchangers (HXs) and air-to-refrigerant evaporators and condensers is located at ORNL. The loop has a variable-speed blower capable of delivering 7500 cfm of air against a pressure drop of 4 in. water. It is equipped with an air heater, a steam injector, and a chilled water coil to control the temperature and humidity of air entering the test HX over a range of about 40 to 120F and 40 to 90%, respectively. A refrigerant circulation subsystem is capable of supporting evaporation or condensation loads of up to 3 tons in the test HX and operating pressures of up to 650 psig. The refrigerant-handling portions of the subsystem are compatible with all HFC refrigerants of interest as well as NH3 and CO2 (evaporating only).

Absorption Heat and Mass Transfer Test Loops

Two test stands are available at ORNL for testing the heat and mass transfer components of absorption heat pumps that use ammonia-water (NH3-water) and lithium bromide-water (LiBr-water) as the working fluids. The focus of work to date has been to formulate and validate strategies to improve the absorption heat and mass transfer process in order to improve overall system performance and to downsize the absorber.

The LiBr-water rig is configured to test either vertical or horizontal absorbers (single tube or tube bundle). All line connections to the absorbers are fabricated from 304L stainless steel. The effect of non-condensibles is minimized through extensive leak checking using a mass spectrometer and has been certified to a leak rate of <107 atm-cc/s. The vertical absorber test section is made of Pyrex glass for flow visualization of the falling film. The horizontal test section has Pyrex glass end plates to allow visualization of the falling film.

The NH3-water rig is used to test heat and mass transfer characteristics of NH3-water based solutions. The test absorber installed in the loop is a wound coil made of low carbon-steel with 58 turns (tube diameter is 0.5 in. O.D. and coil diameter is 4.5 in. between centers).

Corrosion Test Laboratory

Automated electrochemical corrosion instruments are available in this facility at ORNL. These instruments use the linear polarization (or polarization resistance) technique. This technique is a quick and nondestructive method of estimating the uniform corrosion rate of different materials in various absorption fluid mixtures. The corrosion probes are installed in several pressure vessels that can be used to measure corrosion rates over a wide range of operating temperatures and pressures.

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