SU767570A1 - Device for measuring quantity of heat - Google Patents

Description

resistance of the direct coolant flow, connected in series with resistor 4, first and second circuits, consisting respectively of series-connected resistors 5, 6 and 7, 8, switch 9, controlled current source, which includes current source 10 and switch 11, a time-pulse voltage converter operating on the principle of double integration, including an integrator 12, a null-organ 13, a control unit 14, a frequency generator 15, a reference unit 16, a summing unit 17.

The device works as follows.

In the first cycle, for a time interval of duration T, the key 9 according to the signal from the control unit 14, the time-pulse voltage converter is closed, and the key 11 is open. From the flow meter 1, the bridge circuit receives a current 1, the magnitude of which is proportional to the flow rate of the heat carrier. From the output of the bridge circuit, the input of the integrator 12 receives a voltage, the magnitude of which is determined by the magnitude of the current. and the state of the bridge circuit. The voltage at the integrator output increases.

After a time signal, from the control unit 14, the key 9 is opened, the key. 11 closes - and the signal to the input of the comparator unit 16 permits the passage of pulses from the reference frequency generator 15 to the summing unit 17. The integrator receives a voltage proportional to the current Ig of the source 10 and determined by the state of the bridge circuit. The integrator is discharged. The moment of the integrator's discharge is fixed by the null organ 13, which, through the control unit 14, switches on the key 11, and also interrupts the supply of pulses to the summing unit 17.

The number of pulses arriving at the cyberspace block during the integrator discharge time is determined by the expression

1c (

N-K

T,

Ig (R-HDJ-T

de T ,, R ij - resistance values

thermometers of resistance of direct and obrytnogo flow coolant;

l resistance of resistors 5, 6. bridge circuit;

t.

constant coefficients determined by the bridge circuit resistors; constant coefficient.

The number recorded in the summation block is equal to the amount of heat transferred by the coolant taking into account the nonlinearity of the bridge circuit, the nonlinearity of resistance thermometers and the density of the coolant. ,,

Due to the fact that the input current from the flow meter arrives at the bridge circuit in pulses, and during the discharge of the integrator a very small current flows through the resistance thermometers (resistors 5.6 in magnitude, almost more than others), the input current can be increased several times without fear of overloading resistance thermometers. At the same time, the output voltage of the bridge circuit increases and, accordingly, the measurement accuracy, the sensitivity of the device, increase.

The presence of new elements in the device for measuring the amount of heat favorably distinguishes it from the prototype, as it allows to increase the measurement accuracy, the sensitivity of the device, which allows to expand the scope of its application, as well as to more accurately account for the amount of heat consumed in heat supply systems.

Claims (1)

1. Authors certificate of the USSR 0 No. 528464, cl. G dl K 17/08, 1976. 2, USSR Copyright Certificate No. 25.35190 / 18-10, cl. G 01 K 17/08, 03.10.77 (prototype).