Plus42: incorrect behaviour in equation using temperature UOM

[ht003]

(05-27-2024 01:32 PM)Marco Polo Wrote:  I am starting using Plus42 more seriusly and found a glitch regarding the temperature handling in UOM.
Let's take the usual equation for calculating the LMTD of a heat exchanger:

Code:

'LMDT:LMDT=(DThot-DTcold)/LN(DThot/DTcold)'

Solving for LMDT having, for example

Code:

DThot = 9_°C
DTcold = 6_°C

it shall give 7.3989_°C, as it happens in 48/50 series.
On Plus42 the result is incorrectly -265.751_°C

Apparently 273.15 is subtracted to the correct result expressed in °C.

This behaviour is present in Plus42 v.1.1.11

Cheers
Marco Polo

On an IPAD (IPadOS 17.4.1) PLUS42 V. 1.1.11 delivers the correct result:
7,398910387129295058023730205472203 °C
Best
Dieter (ht003)