HEX Thermal efficiency with return sensor

File: HEX Efficiency Exhaust.doc

Last edition: 2003-03-04

Author: Mikael Krantz

History: 96-02-14/MK First released version.

96-09-30/MK Updated to Menta 1.20
Alarm block has new name and text.
Pri added on alarms.

97-08-27/MK Updated to Menta 3.0

98-12-21/MK New filename

2003-03-04/MK Updated to Menta 4.0

Description

t3 - t4

Formula: -------

t3 - t1

where t1 = Supply temperature before HEX.
t2 = Supply temperature after HEX
t3 = Return temperature before HEX
t4 = return temperature after HEX

Efficiency calculation for Heat exchanger with use of an extract air temperature sensor placed after the heat exchanger. The efficiency is calculated as a value between 0 and 100%. An alarm is set if the efficiency is to low while the HEX control is above a set limit. If the numerator or the denominator are below 2°C, or if the running signal is false, the calculation output is zero, and the alarm interlocked.

Inputs

(Real) Outlet temperature before HEX

(Real) Outlet temperature after HEX

(Real) Outdoor temperature

(Real) HEX Control signal, 0-100%.

(Binary) Running signal

Outputs

(Real) Thermal efficiency 0-100%

(Binary) Low alarm thermal efficiency

Parameters

(Real) EfficiencyLimit 40%

(Real) HEXControlLimit 90%

Public signals

(Real) EfficiencyLimit

(Real) HEXEfficiency

(Real) HEXControlLimit

(Binary) HEXAlarm

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