Standard Heater

Under construction.

Performance

The following performance calculations are applied to all standard heater instances:

Calculation Reference Output Tags
LMTD (Log Mean Temperature Difference) ASME PTC 12.2,S 6.9 .LMTD.use
Heat Transfer Coefficient   .heatTransferCoefficient.use

Calculations

LMTD (Co current)

$$LMTD = \frac{\left ( T_{gasin} - T_{steamin} \right ) - \left ( T_{gasout} - T_{steamout} \right )}{In \left ( \frac{T_{gasin} - T_{steamin}}{T_{gasout} - T_{steamout}} \right )}$$

Where:

  • $T_{gasin}$ = Temperature of gas entering element $(^{o}C)$
  • $T_{steamin}$ = Temperature of gas entering element $(^{o}C)$
  • $T_{gasout}$ = Temperature of gas entering element $(^{o}C)$
  • $T_{steamout}$ = Temperature of gas entering element $(^{o}C)$

In CAS terms:

$$element.lmtd.use = \frac{(ob.c2in.prop.temp.use - ob.c2in.prop.temp.use) - (ob.c2out.prop.temp.use - ob.c1in.prop.temp.use)}{In \left ( \frac{ob.c2in.prop.temp.use - ob.c1in.prop.temp.use}{ob.c2out.prop.temp.use - ob.c1out.prop.temp.use} \right )}$$

LMTD (Counter current)

$$LMTD = \frac{\left ( T_{gasin} - T_{steamin} \right ) - \left ( T_{gasout} - T_{steamout} \right )}{In \left ( \frac{T_{gasin} - T_{steamout}}{T_{gasout} - T_{steamin}} \right )}$$

In CAS terms:

$$element.lmtd.use = \frac{(ob.c2in.prop.temp.use - ob.c2in.prop.temp.use) - (ob.c2out.prop.temp.use - ob.c1in.prop.temp.use)}{In \left ( \frac{ob.c2in.prop.temp.use - ob.c1out.prop.temp.use}{ob.c2out.prop.temp.use - ob.c1in.prop.temp.use} \right )}$$

Heat Transfer Coefficient

The heat transfer coefficient is characterising parameter that incorporates the heat transfer coefficient and the geometry of the standard heater elements and is defined as:

$$HTC = \frac{Q}{\Delta T_{LM}}$$

Where:

  • $HTC$ = Heat Transfer Coefficient (kW/$^{o}C$)
  • $Q$ = Heat Flow from steam/gas (kW)
  • $\Delta T_{LM}$ = Log Mean Temperature Difference $(^{o}C)$

In CAS terms:

$$element.heatTransferCoefficient.use = \frac{element.c1.dQ.use}{element.lmtd.use}$$

A comparison of the actual and design values together with the components historical values, will determine whether the standard heater element is operating within an acceptable band from its design point.

Contact us

Phone

+617 3229 3333

Address

28E Gladstone Rd
Highgate Hill, QLD 4101
Australia