technical information

SteamTab Quad™ Technical Information

Introduction

SteamTab Quad, makes available in a single spreadsheet add-in package the property values of water and steam based on any one of 4 sets of universally recognized formulations. These formulations include two sets of scientific formulations – the older NBS/NRC-84 and new IAPWS-95, and two sets of industrial formulations – the older IFC-67 and new IAPWS-IF97.

Design

SteamTab Quad uses fundamental equations to calculate all steam properties with no interpolation or curve fits to raw steam data. With SteamTab Quad, users have a choice of basing their steam property calculations from either the scientific formulation, or the industrial formulation. The formulations used in SteamTab Quad and their references are shown in the following table.

Pressure (P, bar):    0 <= P <= 100,000
Temperature (T, K): 190 <= T <= 5000

Pressure (P, bar):       0 <= P <= 1,000
Temperature (T, K): 273.15 <= T <= 1,073.15 
                   (for P <= 1,000)

                   1073.15 <= T <= 2,273.17
                   (for P <= 100)

Pressure (P, bar):    0 <= P <= 30,000
Temperature (T, K): 260 <= T <= 2,500

Pressure (P, bar):    0    <= P <= 1,000
Temperature (T, K): 273.16 <= T <= 1,073.15

Note: SteamTab does not include properties for ice.

Implementation

The core routines in SteamTab are written in C++ and compiled using Microsoft's Visual C++ into a standalone dynamic link library (DLL). All of the routines use double precision arithmetic (8 byte real). In addition to using standard compiler optimization techniques to speed-up calculations, SteamTab employs an innovative and proprietary "caching" strategy to minimize repetitive calculations. Our internal benchmarks indicate that these optimizations give a performance boost of 2 to 5 times over the un-optimized and "un-cached" versions.