E-Code

Heat exchanger by ε-NTU, checked with LMTD, step by step — a TI-89 Titanium program

By E-Code · updated

HEATX is a TI-89 BASIC program for the TI-89 Titanium. Inlet temperatures, the two capacity rates and UA, counterflow or parallel flow. Step by step: Cmin, Cmax, Cr and NTU, the effectiveness, the heat rate, both outlet temperatures from the two energy balances solved together by the algebra system, then the LMTD method as a check that gives the same q.

What it asks for and what it shows

It asks for 5 values at its prompts, after you pick option 1 from its menu. In the example below it shows Cmin W/K, Cmax W/K, Cr=Cmin/Cmax, NTU=UA/Cmin, ε, q W, Tho °C, Tco °C, LMTD °C, UA·LMTD W, 2 COUNTERFLOW ε, 4 OUTLETS (CAS system), 5 CHECK WITH LMTD, 6 ANSWER.

Example run

One of its oracle test cases. The inputs are typed in order, and the results are the values the case expects on the screen.

StepValue
You enter
Menuoption 1
Input 1150
Input 220
Input 32000
Input 43000
Input 52500
The screen shows
Cmin W/K=2000
Cmax W/K=3000
Cr=Cmin/Cmax=0.6666666667
NTU=UA/Cmin=1.25
ε=0.6079492814
q W=158066.8132
Tho °C=70.96659342
Tco °C=72.68893772
LMTD °C=63.22672527
UA·LMTD W=158066.8132
Text2 COUNTERFLOW ε
Text4 OUTLETS (CAS system)
Text5 CHECK WITH LMTD
Text6 ANSWER

How it's checked

4 test cases, each checked against an independent method. Replayed key by key on a virtual TI-89 Titanium, they make 64 checks.

How E-Code checks every program

Run it or put it on your calculator

Related programs

All TI-89 Titanium engineering programs · All TI-89 Titanium programs