252
Chapter 25
Hollow receiving surfaces , made of copper and situated on an annular
thermobattery are placed into a cylindrical copper case. The thermobattery is
made of Constance wire, which has been coiled on an insulation ring and the
outer part of which is galvanically covered by a copper coating. The
diameter of the wire is 0.1 mm, the number of coils is about 200. A double
layer of epoxy-impregnated paper with the thickness of 0.05 mm insulates
the thermobattery from the receiving surfaces and the case. To reduce heat
loss, the receiving surfaces are surrounded by foamed plastic insulation . The
space between the details is filled with an epoxide component, which avoids
the effects of humidity on the thermobattery. Equal sensitivity of receiving
surfaces is adjusted individually for each instrument with the help of heat
shunts, which increase thermal conductivity between the receiving surfaces
and the case when the screws compress the plasticine column between the
screws and the receiving surfaces. The accordance between the angular
characteristic of the black glossy receiving surfaces and the cosine-law is
achieved by shaping them in the form of cavities (elementary models of the
black body).
The calibration of the net radiometer in the solar radiation spectral region
has been provided in the pyrheliometric scale by the Sun and shadow
method. To calibrate the net radiometer in the infrared (thermal) radiation
region a special device—a double black body—has been designed and a
suitable method developed.
Calibration of net radiometers by hemispherical low-temperature
radiators is rather complicated due to considerable non-radiative heat
transfer between the radiation receiver and the black body. As a result,
sources of infrared radiation with a narrow aperture have been used lately for
this purpose (Drummond, 1970, Faraponova, 1968). Since thermal radiation,
measured with a net radiometer in field conditions, falls on the receiving
surfaces from the hemisphere, it would be methodically correct to carry out
the calibration of the sensors with the help of radiators with a wide aperture.
For this kind of calibration, a radiation standard was designed. The standard
consists of two low-temperature black bodies with an aperture of
A
method for the elimination of non-radiative heat transfer has also been
devised.
Chapter 25
Hollow receiving surfaces , made of copper and situated on an annular
thermobattery are placed into a cylindrical copper case. The thermobattery is
made of Constance wire, which has been coiled on an insulation ring and the
outer part of which is galvanically covered by a copper coating. The
diameter of the wire is 0.1 mm, the number of coils is about 200. A double
layer of epoxy-impregnated paper with the thickness of 0.05 mm insulates
the thermobattery from the receiving surfaces and the case. To reduce heat
loss, the receiving surfaces are surrounded by foamed plastic insulation . The
space between the details is filled with an epoxide component, which avoids
the effects of humidity on the thermobattery. Equal sensitivity of receiving
surfaces is adjusted individually for each instrument with the help of heat
shunts, which increase thermal conductivity between the receiving surfaces
and the case when the screws compress the plasticine column between the
screws and the receiving surfaces. The accordance between the angular
characteristic of the black glossy receiving surfaces and the cosine-law is
achieved by shaping them in the form of cavities (elementary models of the
black body).
The calibration of the net radiometer in the solar radiation spectral region
has been provided in the pyrheliometric scale by the Sun and shadow
method. To calibrate the net radiometer in the infrared (thermal) radiation
region a special device—a double black body—has been designed and a
suitable method developed.
Calibration of net radiometers by hemispherical low-temperature
radiators is rather complicated due to considerable non-radiative heat
transfer between the radiation receiver and the black body. As a result,
sources of infrared radiation with a narrow aperture have been used lately for
this purpose (Drummond, 1970, Faraponova, 1968). Since thermal radiation,
measured with a net radiometer in field conditions, falls on the receiving
surfaces from the hemisphere, it would be methodically correct to carry out
the calibration of the sensors with the help of radiators with a wide aperture.
For this kind of calibration, a radiation standard was designed. The standard
consists of two low-temperature black bodies with an aperture of
A
method for the elimination of non-radiative heat transfer has also been
devised.