Page 317 - Теория кавитации

4. A rotating fluid, having reached a hydraulic brake, when striking its surface, gives off as heat some of
the kinetic energy expended by the pump to form a rotational motion. At the same time, the cavitation bubbles
“collapse” generate heat at the moment of force.
5. When the liquid reaches a certain temperature, the pump shuts off, the liquid returns to its original state,
and after cooling it to a predetermined temperature, the pump turns on.
Preliminary assessment of the energy and technical and economic efficiency of an experimental vortex
heat generator:
As shown in the first stage of R & D (in 2014-2016: [10]-[12]), the literature review and analysis of
scientific works, the most discussed issues are calculations to determine the energy efficiency rating of vortex
heat generators. Here, the opinions of various authors are different, despite simple calculations. In addition to
the traditional concept of "efficiency" (efficiency factor), the concept of "ECC" (energy conversion coefficient)
was introduced. Although by definition, and the physical entity, in our opinion, significant differences are not
observed.
We define the ECC for the two above-mentioned variants of the experiments carried out, according to the
data obtained (Table 2).
The calculation of the ECC is determined by the following dependency:

= 1 · 100% (1)
2

Where, Q1 is the useful energy obtained in the VHG system as a result of its functioning.
Q2 - energy consumed by a centrifugal pump (CP).
The value of Q1 is determined by the following dependency:

Q1 = c·m·∆T (2)

Where, c is the heat capacity of the coolant (for water - 4.2 × 103 J / kg × K);
m is the specific gravity (volume) of water in the system;
∆T is the temperature difference in the system before and after switching on the VHG.
The value of Q2 is determined by the formula:

Q2 = P·∆t (3)

Where, Р - the set power of the centrifugal pump (Р = 3,7 kW);
Δt is the operating time of the CP.

Table 2 - Thus, below are the calculation results for the first test case:
# Time in minutes The temperature value The volume of water in the
system (liters)
(in the tank), C
о
1. The inclusion of VHG: t1= 11:14 min. T1 = 22

2. Shut down VHG: t2=11: 36 min. T2 = 55 15

3. t = t2 - t1= 22 min T = T2 - T1 = 33
ECC of VHG 1,2

For the results of experimental testing of the second variant (according to Table 2) of the VHG, depending
on the volume of water in the system (the number of connected radiators in the system), were obtained different
values of the ECC of VHG were obtained.
The calculation results are shown in Table 3.

316