Page 74 - libroBrevetti

Department of Engineering, ICT and Technologies for Energy and Transport Patent Title Thermal-hygrometric monitoring of wide surfaces by IR Thermography. Ref. CNR 1721 Assignee(s): CNR CNR InsƟƚute: ITC Main Inventor: Paolo Bison Countries: IT Priority date: 05/05/2006 Abstract The inveŶƟŽn refers to a method that allows to measure the air ƌĞůĂƟve humidity, absolute humidity, and dew point by means of a thermographic equipment; this method is relevant – also thanks to a ƉĂƌƟĐƵůar device described in this patent - for wide surfaces (i.e. a wall), parƟĐƵůĂrly for arƟsƟc and historical patrimony. The moisture content of the wall is determined through the distrŝďƵƟon and evolƵƟŽn of surface temperature by means of speciĮc algorithms that ideŶƟĨy the risk areas. The ŽƉƟcal nature of the monitoring makes the scan fast and contactless. Background The main applicaƟons of IR thermography for the humidity deteĐƟŽn are based on: a) absŽƌƉƟŽn of infrared ƌĂĚŝĂƟon ;ŽƉƟĐal method); b) vaƌŝĂƟŽn of the porous material thermal propeƌƟes depending on the humidity content (dynamic thermal method); c) evaporĂƟve cooling (passive thermal method). Technology The method allows to quanƟtĂƟvely determine the main thermo-hygrometric parameters both of the air and of the solid surface. The device, called ‘Irpsicro’, is posŝƟoned close to the surface to be monitored and the temperature Ěŝīerence between ‘wet bulb’ and ‘dry bulb’ is measured by an IR camera. At the same Ɵŵe, the moisture content of the surface (i.e. a wall) is measured depending on the thermal eīects due to evapŽƌĂƟŽn. Advantages and ApplicaƟons The evapŽƌĂƟǀĞ process, due to the ŵŝŐƌĂƟŽn of salts inside the materials, is the main responsible of the degradĂƟŽn of the surfaces of the ĂƌƟƐƟĐ and historical patrimony. The key points of the humidity analysis are the knowledge of the water content and of the exchange of vapour between surface and air. All the measurements are carried out with the same instrument reducing the inter-ĐĂůŝďƌĂƟŽn errors. Development stage A prototype of the equipment, with a high level of automĂƟon, is available at ITC-CNR in Padova. It consists of a IR camera with microbolometer sensor that is mounted on a pan-Ɵůƚ head and a grid of ‘Irpsicro’. The instrument was already ƵƟůŝzed in several measurement campaigns: Chiesa di Baver (TV), La Torrazza del Castello di Masino (TO), Chiesa di San Vito L’Aquila (AQ), Abbazia di Novalesa (TO), Chiesa di San GoƩardo Asolo (TV). 65