Modeling/Analytical Capabilities

General vapor compression cycle models. Three basic vapor compression cycle simulation models are available in-house for pure and mixed refrigerants--REFCYCLE, BICYCLE, and TRICYCLE. All use the NIST REFPROP program for refrigerant thermodynamic and transport properties. REFCYCLE calculates the theoretical cycle performance of refrigerants at specified heat exchanger temperatures (mean or dew point), superheat/subcooling/intercooling levels, and compressor efficiencies. BICYCLE simulates cycle performance in both heating and cooling modes (bimodal) with specified external flows or temperature changes (for a variety of fluids), heat exchanger conductances (UAs), and capacity or compressor size. TRICYCLE extends BICYCLE to include refrigerant-specific heat transfer and pressure drop effects in the heat exchangers and allows tube diameter and circuitry to be optimized for each refrigerant. For possible application of these models to your research needs, contact Keith Rice.

DOE/ORNL Heat Pump Design Model (HPDM). The HPDM is a hardware-based steady-state performance simulation and design tool for air-to-air heat pumps. Single- and variable-speed versions are available; the latest version includes the leading near-azeotropic HFC alternatives. The program runs extremely quickly (< 1 second on a 90-MHz Pentium) for a single design point simulation and has versatile input options allowing simultaneous two-parameter studies of many system design variables. The HPDM also has off-design charge inventory balancing capability for assessing heat pump performance over a wide range of heating and cooling ambients with a variety of flow control devices. This model has been widely distributed to industry, university, and research groups. A web version of the latest distribution model is now available online.

ABsorption SIMulation model (ABSIM). ABSIM is a modular computer code for simulation of absorption systems. This modular code is based on unit subroutines containing the governing equations for the system's components and on property subroutines containing thermodynamic properties of the working fluids. Eleven absorption fluids are presently available in the code's property database, and twelve units are available to compose practically every absorption cycle of interest. ABSIM may be used for evaluating new cycles and working fluids and to investigate a system's behavior in off-design conditions, to analyze experimental data, and to perform preliminary design optimization. A graphical user interface enables the user to draw the cycle diagram on the computer screen, enter the input data interactively, run the program, and view the results either in the form of a table or superimposed on the cycle diagram. Special utilities enable the user to plot the results and to produce a PTX diagram of the cycle. This model has been widely distributed to industry, university, and research groups. For further information on this model, contact Abdi Zaltash.

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