METHOD FOR MEASURING HEAT GAINS OF COOLED IR RECEIVERS Russian patent published in 2023 - IPC G01K17/00 G01F5/00 

FIELD: thermophysical measurements.

SUBSTANCE: invention relates to a technique for thermophysical measurements, namely, to a technique for determining heat inflows to cooled structural elements of infrared radiation receivers from the environment in laboratory and manufacturing conditions. A method for measuring the heat gain of IR photodetectors is proposed, the method comprising the process of measuring the flow rate of liquid nitrogen evaporating from the well of the receiver cryostat, the process of controlling the temperature of the bottom of the well Т_∂ and determining of heat gain, while the value of consumption of gaseous nitrogen V_i is measured at the stabilized evaporation section for any moment of time t_i, and then determine the heat gain q_i by the formula q_i=V_i⋅ρ⋅r; where q_i - heat gain to the cryostat from the environment, W; V_i - volumetric flow rate of gaseous nitrogen, cm³/s; ρ - density of gaseous nitrogen, g/cm³ ; r is the latent heat of vaporization of nitrogen, J/g; the final time point t_k is fixed when the nitrogen consumption becomes equal to zero, after which, using the obtained values of q_i, the approximating dependence of the change in heat gain over time is determined: q_i =A⋅exp[b⋅(t_k -t_i )]; where A and b are constant coefficients determined by solving the resulting system of equations q_i=f(t_k -t_i) using, for example, the least squares method, and determine from the obtained approximating dependence the true value of heat gain q_k for t_k, substituting value (t_k -t_i)=0, corresponding to the moment of complete evaporation of nitrogen, i.e. q_k=A.

EFFECT: increased reliability of measurement results.

1 cl, 2 dwg, 2 tbl