THERMODYNAMICS FOR CULTURAL HERITAGE

PhD student: Maria Concetta Di Tuccio

Supervisor: Dr. Nicola Ludwig University of Milan

Assistant Supervisor: Dr. Adriana Bernardi ISAC- CNR, Padua

Milan - 15th October 2012

Development points

MAIN OBJECTIVE: to deepen the measurement methodology of the surface temperature of the works of art with remote sensing

Evaluation of the problems related to the measure of surface temperature by mean of remote traditional tecniques: radiometer and thermocamera Test of the working of the new sensor:

calibration in climatic chamber and thermal bath; evaluation of the influence of the sensor self-heating; determination of the best measuring conditions (distance from the surface to be

monitored).

Evaluation of the risk of damage related to thermo-hygrometric stress on different materials, particularly wood and plaster

Field tests: S. Croce Museum, Florence

Why the monitoring of the surface temperature is important?

The surface temperature is strongly influenced by the environment

The materials are subjected to changing microclimatic conditions

Evaporation processes

PLASTER

Salts cristallization

Detachment and loss

WOOD

Thermal gradients

EMC variation

Dimensional variations

Cracks, detachment of paint layer

Contact sensor

Quasi-contact sensor

Drawback:

The sensor need to be in contact with the

surface → difficult to realize

Not usable for distant and/or untouchable

surfaces

Advantages:

There is not the problem of the

emissivity

Measuring the surface temperature in Cultural Heritage

Radiometer

Remote sensing

Thermocamera

The measures are strongly influenced by the reflected radiation

radiometer thermocamera

Spot monitoring Continuous monitoring

Accurate measurement : setting of the E in each point of the surface

Less accurate measurement : setting of the same E in the area investigated

Radiometric measures S.Croce Museum - Firenze

Deposizione della Croce of Francesco

Salviati

T(°C)

T(C°)

Calibration of the new sensor

climatic chamber

Thermal bath

More stable

More precise calibration

Calibration in real condition

Temperature of the black body immersed in the thermal bath:

10°C – 20 °C – 30 °C – 40°C – 50 °C

Temperature of the black body:

10°C20°C - 30°C 40°C - 50°C

Temperature of climatic chamber:

10°C - 20°C30°C - 40°C

50°C

Insulation materials

Black body at variable temperature for calibration in climatic chamber

Reflective material

Pt100at the bottom

Monitoring of the black body

Tm: 37,7 °C

Pt100 temperature: 37,6 °C

Tm: 40,3 °C

Pt100 temperature: 40,2 °C

Tm: 45,8°C

Pt100 temperature: 45,9 °C

Tm: 50,05 °CPt100 temperature: 50,3 °C

Monitoring of the black body

Work plan for the near future

Validation of the new instrument

To separate the electronic part and the sensor To calibrate in the climatic chamber and in thermal bath

To evaluate the influence of the self-heating of the sensor on the measures

To determine the best distance between the sensor and the surface