**4. Computational methods**

**3.3 Experimental uncertainty and errors**

*Inverse Heat Conduction and Heat Exchangers*

tainty of each instrument were evaluated.

uncertainty of flow measurement was �2.34%.

�0.63°C.

was �0.012 bar.

variables in Re:

Getting,

= 0.0665 or 6.65%.

= 0.0625 or 6.25%

**32**

The used instruments were well calibrated, and the margin of error and uncer-

• Flow meters type LZS-25 used to measure the flow rate of heat transfer fluids were calibrated using a scaled container and time recording technique, which is well identified as a standard procedure for flow meter calibration. The relative

• Differential manometer was calibrated against another certified manometer

Organization for Standardization and Quality Control (COSQC)—Baghdad— Iraq [certificate number PRE/918/2016 dated 06 Oct. 2016]. Max uncertainty

type Lutron (PM-9100). The relative uncertainty was �2.1%.

• The two pressure gauges were calibrated and certified by the Central

The possible error in the prediction of Re and Nu was estimated. The

uncertainties of the measuring instruments used for measurements of relevant

*Re* <sup>¼</sup> <sup>4</sup> *<sup>m</sup>*\_

∙*V*\_ � �<sup>2</sup>

> *V*\_ � � � � <sup>2</sup>

Uncertainty in Nu values was estimated by Eq. (19) using the uncertainties of the measuring instruments used for measurements of relevant variables in Nu, as

> *h* � � � � <sup>2</sup>

*πμ<sup>d</sup>* <sup>¼</sup> <sup>4</sup>*ρV*\_

� �<sup>2</sup> " #<sup>0</sup>*:*<sup>5</sup>

<sup>þ</sup> *<sup>σ</sup>Re σd* � �

þ

þ

� � � � <sup>2</sup> " #<sup>0</sup>*:*<sup>5</sup>

� � � � <sup>2</sup> " #<sup>0</sup>*:*<sup>5</sup>

*Δd d*

*Δd d*

∙ *d*

*πμ<sup>d</sup>* (16)

(17)

(18)

(19)

uncertainty in Re values was estimated by Eqs. (16)–(18) using the

*σV*\_ � �

*<sup>Δ</sup> Re <sup>=</sup> Re* <sup>¼</sup> *<sup>Δ</sup>V*\_

*<sup>Δ</sup>Nu=Nu* <sup>¼</sup> *<sup>Δ</sup><sup>h</sup>*

*<sup>Δ</sup> Re* <sup>¼</sup> *<sup>σ</sup>Re*

• Thermocouple type-K used in this study to measure temperature of surfaces. Thermocouple type-K probes were used to measure the fluid temperature. All thermocouples and probes were calibrated and certified by the Central Organization for Standardization and Quality Control (COSQC)— Baghdad—Iraq [certificate number 734/2016 dated 30 Oct. 2016]. Mean uncertainty within the temperature measurement in the experiment was
