Method of monitoring the degree of clogging of the heat exchangers in the instrument cabinet

 

(57) Abstract:

The invention relates to the field of technical diagnostics, in particular to control the degree of clogging of the heat exchangers in the instrument Cabinet with liquid cooling. Essence: the task of the invention is to simplify the method and increase its reliability. The solution to this problem is achieved in that in the method, based on the determination of fluid flow through the heat exchanger, introduced new operations: determine the dependence of Q = f(T) of the fluid flow flowing through nesesarry the heat exchanger, the temperature change at a particular point on the surface desasosiego heat exchanger during heating its reference heater during a fixed time tf; determine the temperature change at the same point on controlled heat exchanger during the heating of the reference heater for time tfand flow into the instrument Cabinet nominal flow rate; the actual rate of fluid through a controlled heat exchanger is determined by the dependence of Q = f(T). To improve the accuracy of the method point on the surface desasosiego heat exchanger choose on the drain pipe. To simplify the method of determining according to Q = f(T) produce deplovment, located above. 2 C.p. f-crystals, 2 Il.

The invention relates to the field of technical diagnostics, in particular to control the degree of clogging of the heat exchangers in the instrument Cabinet with liquid cooling.

When operating the instrument Cabinet with liquid cooling possible clogging of the heat exchangers (increase the speed of cooling liquid line), which reduces the speed of the coolant in the heat exchangers, overheating of the cooling modules and the failure of the device. So I need to control the degree of clogging of the heat exchangers.

The known method of monitoring the degree of clogging of the heat exchangers in the instrument Cabinet by unplugging from the cooling Cabinet, connect to a special liquid system which allows to measure the flow of fluid passing through the heat exchanger, for example, a rotameter [1].

There is also known a method of monitoring the degree of clogging of the heat exchangers in the instrument Cabinet without disconnecting from the cooling Cabinet by installing in the liquid line of each heat exchanger device for determining the flow rate of water passing through the heat exchanger, for example, Converter electromagnetical control the degree of clogging of the heat exchangers in the instrument Cabinet without disconnecting from the cooling system of the device [2].

In accordance with this method determines the flow of liquid in a controlled exchanger according to the EMF induced in a conductive liquid moving in a magnetic field, the value of which depends on the speed (flow) of the fluid. To do this, in the liquid line of each heat exchanger install the Converter of electromagnetic flow meter, representing a pipe section made of magnetic material (stainless steel, plastic, etc.,) in which are mounted two electrodes. At the location of the electrodes outside of the pipeline have a magnet - pole electromagnet. The degree of clogging of the heat exchanger is determined by comparing the measured flow rate from nominal flow rate.

The disadvantage of this method is its complexity, because of its implementation in the design of the instrument Cabinet, you must have a large number of converters electromagnetic flow meter. In addition, the complex design of the flow meter and the measuring circuit.

Object of the invention is the simplification of the method and increase its reliability.

The solution to this problem is achieved in that in the method, based on the determination of fluid flow through C nesesarry the heat exchanger, from change of temperature T at a particular point on the surface desasosiego heat exchanger during heating its reference heater during a fixed time tf;

determine the change in temperature at the same point on controlled heat exchanger during the heating of the reference heater for time tfand flow into the instrument Cabinet nominal flow rate;

the actual flow rate of fluid through a controlled heat exchanger is determined by the dependence of Q = f(T) .

To improve the accuracy of the method point on the surface desasosiego heat exchanger choose on the drain pipe.

For simplification of the method of determination according to Q = f(T) is produced on the lower heat exchanger instrument Cabinet, and the liquid in it is served under the pressure at which it enters the heat exchanger located above.

The invention is illustrated in Fig.1, which schematically shows a front view of the instrument Cabinet, and Fig. 2, which presents the dependence of Q = f(T).

The proposed method is implemented as follows.

Pre-determine the dependence of Q = f(T) on netuserenum the heat exchanger. This operation can be performed with high precision is on the lower heat exchanger. To do this you must first make sure that the heat exchanger is not clogged. With a sufficient degree of accuracy for practical use it do so. In-dash six-story Cabinet 1 with a nominal flow rate of QW= 480 kg/h containing twelve exchangers 2, which are connected in parallel to a pressure head 3 and the drain 4 pipelines to supply water with a flow rate approximately equal to half of the nominal flow rate Q = QW/2 = 480/2 = 240 kg/h, and a temperature different from the ambient temperature of not less than 10oC. multiple heat exchangers, including the bottom, measured in the center of the working surface 5 by means of a thermocouple temperature T. If the temperature T on the lower heat exchanger coincides with the temperature measured on other heat exchangers, it is chosen to define the relation Q = f(T) . If the temperature does not match the measurement with the same costs and the temperature of water is performed on the lower heat exchanger of another Cabinet, etc. to select the desired heat exchanger.

At the bottom of the heat exchanger set the reference heater 6 with a capacity of N = 1.5 kW, pressing it working surface coil device 7 to the working surface of the heat exchanger. Aucat capacity 9 level 10 water located slightly below the level of the heat exchanger located above, under the drain pipe 11 instrument Cabinet set the measuring Cup 12, open the valve 13 and serves water in the instrument Cabinet, determine the water flow rate Q1with stopwatch and a measuring capacitance, measured temperature T1in point 14 of the surface of the drain pipe of the heat exchanger located at a distance of 5 mm from the end surface of the heat exchanger, a heater at time tf= 5 min, again measure the temperature at the point 14 For measurement time constant the water level (pressure), adding it. Determine and obtain the first point according to Q = f(T) . Then the heater can stand up to the ambient temperature, is lowered below the water level in the tank 10 and perform the above operation for less water and Q2define T2and the second point based. Thus, changing to zero water consumption and determining the appropriate T get the required number of points to build according to Q = f(T)

To control the degree of clogging of the heat exchangers in the instrument Cabinet to a controlled heat exchanger set the reference heater, press its screw device to the working surface is at a distance of 5 mm from the end surface of the heat exchanger, water is supplied to the instrument Cabinet with a nominal flow rate of QW= 480 kg/h, the consumption of water through nesesarry the heat exchanger should be Qn= 480/12 = 40 kg/h, measure the temperature at the discharge pipe of the heat exchanger, a heater at time tf= 5 min, again measure the temperature on the discharge pipe. Then the difference between the measured temperature T on the drain pipe is determined by the dependence of Q = f(T) is the actual water flow rate in heat exchanger Qk. If Qk= Qnthen conclude that the heat exchanger is not clogged. In the case of Qto<Qdetermine the percentage of the degree of clogging of the heat exchanger.

The use of the proposed method of monitoring the degree of clogging of the heat exchangers in the instrument Cabinet compared to existing allowed due to the exclusion of additional devices for measuring fluid flow through a heat exchanger to simplify the method and to increase its reliability.

Experimental verification of the method confirmed its simplicity, reliability and efficiency.

1. Method of monitoring the degree of clogging of the heat exchangers in the instrument Cabinet, based on the determination of fluid flow through the heat exchanger and comparing it with nesesarry the heat exchanger, from change of temperature T at a particular point on the surface desasosiego heat exchanger during heating its reference heater during a fixed time tfthen determine the temperature change at the same point on controlled heat exchanger during the heating of the reference heater for time tfand flow into the instrument Cabinet nominal flow rate and the actual flow rate of fluid through a controlled heat exchanger is determined by the dependence of Q = f(T).

2. The method according to p. 1, characterized in that the point on the surface desasosiego heat exchanger choose on the drain pipe.

3. The method according to PP. 1 and 2, wherein defining the relationship Q = f(T) is produced on the lower heat exchanger instrument Cabinet, and the liquid in it is served under the pressure at which it enters the heat exchanger located above.

 

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