The hydraulic elevator is installed on the supply pipe at the entrance to the building in open heating systems from heating networks (see Fig. 2.2) and by mixing the cooled water from the return pipeline to the superheated water, the heating network produces a heat carrier with a design temperature of 95–105 ° С.
| Diagram of hydraulic elevator is shown in Fig. 3.7. By design, the hydraulic elevator is a water-jet pump — at the nozzle exit, due to the reduced diameter, the coolant velocity increases, and the pressure, according to the laws of hydraulics, decreases. With proper selection, this pressure decreases below the pressure in the return pipeline, and exhaust chilled water is sucked in. | |
| Fig. 3.7. Hydraulic elevator circuit: 1 - from the heating system; 2 - from the return line of the heating system; 3 - to the supply line |
The hydraulic elevator is characterized by two main parameters - the throat diameter dg and the nozzle diameter dc .
The diameter of the neck dg , mm, determined by the formula
(3.10)
where Gcm - coolant flow in the first section from the elevator to the heating system, kg / h, determined by hydraulic calculation [formula (2.12)]; D Рнас - circulation pressure in the heating system, Pa, is determined by the formula (2.10).
According to the diameter of the neck (Table 3.4), the number of the serial hydraulic elevator (VTI-Mosenergo or another type) is selected.
Table 3.4
Standard hydraulic elevators VTI-Mosenergo
Elevator number | one | 2 | 3 | four | five | 6 | 7 |
The diameter of the neck dg , mm | 15 | 20 | 25 | thirty | 35 | 47 | 59 |
The nozzle diameter dc , mm, is determined by the formula
, (3.11)
where U must be defined earlier by the formula (2.11).
Example 5. Selection of hydraulic elevator.
Baseline: building and heating system to take the characteristics in accordance with examples 1, 2 and 3.
Decision. Earlier in the examples, the main parameters of the heating system are determined, which are necessary for selecting an elevator: Gcm = G1 = 1678 kg / h,
Dpnas = 13700 Pa, U = 1.286.
By the formula (3.10) is determined by the diameter of the neck
mm
A serial hydraulic elevator VTI-Mosenergo No. 1 with a neck diameter of 15 mm was adopted.
The diameter of the nozzle is determined by the formula (3.11)
»7 mm.
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