RU2735118C1 - Device for converting mechanical energy of oil into heat energy - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to conversion of mechanical energy into thermal energy, specifically oil heating in reservoir included in hydraulic system. Device for conversion of mechanical energy of oil into heat contains oil tank, pressure and drain lines, pump, chokes installed parallel in pressure main line and hydraulic distributor. In pressure line three throttles are installed, and hydraulic distributor is made with possibility of series shutdown of throttles depending on oil pressure.

EFFECT: ensuring oil heating with volume of not less than 0_5 m³ at low ambient temperatures.

3 cl, 1 dwg

Description

The invention relates to the field of converting mechanical energy into thermal energy, namely, heating the oil in a tank included in the hydraulic system, by throttling, and can be used, for example, in auto fuel refueling vehicles (ATMZ) during operation, including at low temperatures.

There is a known method of generating heat (RU2241919C1), in which the liquid is pumped through a closed office, when the liquid exits the pump, it is throttled, and when the liquid enters the pump, pressure is released in it.

According to the description of the invention to the specified patent, the patented solution is not designed for use at low temperatures (water is used as the working fluid), in addition, the device disclosed in the description, which implements the method, cannot solve the problem of heating a liquid (oil) with a volume of at least 0 , 5 m ³ , at low temperatures for a comparable time (26 min.).

As a prototype, a heating system for the cab of a vehicle with a hydraulic system (SU1082635A) was chosen, containing a heat exchanger installed in the hydraulic system of a vehicle, a pressure and drain lines, a tank, a pump and a main choke installed in the pressure line for heating the coolant, while it is equipped with sequentially installed in the pressure line of the specified circuit of the hydraulic system, a three-line two-position hydraulic valve and an additional throttle with its hydraulic line, which is connected to the pressure line in front of the heat exchanger, while the throttles are adjustable, with different flow cross-sections: the main throttle with a large cross section, and the additional throttle with a smaller one.

In the known system, adjustable throttles are used, which is a technical difficulty, in addition, the known solution is not directly aimed at heating a large amount of oil as soon as possible.

The problem to be solved by the invention was to provide heating of oil with a volume of at least 0.5 m ³ at low ambient temperatures down to minus 50 ° C, to provide for own needs (for example, in a vehicle) and for the delivery of oil to external consumers. Moreover, oil heating should be carried out as soon as possible.

This problem is solved by a device for converting mechanical energy of oil into thermal energy, containing an oil tank, pressure and drain lines, a pump, throttles installed in parallel in the pressure line and a hydraulic distributor, in which, according to the proposal, three chokes are installed, and the hydraulic valve is made with the possibility of sequentially disconnecting the chokes depending on oil pressure.

If the device is installed on a vehicle (for example, an oil or fuel oil dispenser), the pump is driven from the power take-off (PTO) of the engine of a specialized vehicle. In this case, it is also possible to include in the device additional drain and pressure lines with a pump and a hydraulic distributor made with the possibility of directing the oil flow for delivery to an external consumer, to the hydraulic motor and to the oil tank through an additional throttle.

The invention is illustrated by a drawing.

The device for converting mechanical energy of oil into thermal energy contains an oil tank 1, pressure 2 and drain 3 lines, pump 4, throttles 5 and hydraulic distributor 6 installed in parallel in the pressure line. Pump 4 is driven from the power take-off 7 of the engine of a specialized vehicle.

The device may contain additional drain 8 and pressure 9 lines with a pump 10 and a hydraulic valve 11 configured to direct the oil flow for delivery to an external consumer (through the delivery unit 12), to the hydraulic motor 13 and to the oil tank 1 through an additional throttle 14.

The device works as follows.

The thickened oil in the oil tank 1 at a negative ambient temperature (up to minus 50 ° C) is subjected to forced circulation by means of pump 4 through the pressure 2 and drain 3 lines through the choke system 5, as the temperature rises, the oil pressure at the entrance to the choke assembly begins to fall. To maintain the required pressure and heating rate, throttles 5 are sequentially disabled by means of hydraulic valve 6. The use of exactly three chokes is a reasonable compromise in terms of the required drive power, oil heating time and oil temperature / pressure ratio.

The following is a calculation of the power consumption of pump 4 (NSh100) used to ensure the oil heating process.

The following is a calculation of the required heating power and oil heating time.

Oil tank volume V = 500 liters = 0.5 m ³ .

The density of the oil c = 900 kg / m ³ .

Specific heat c = 1.9 kJ / (kg K).

TTX ATMZ data:

heating time T = 1 min = 60 s;

temperature change Dt = 2 K.

Oil mass in oil tank

. $$m=V\cdot \rho =0.5\cdot 900=450\mathrm{to}r$$

...

Energy required to heat 450 kg of oil by 2 degrees

. $$E=\mathrm{from}\cdot m\cdot \Delta t=1.9\cdot 450\cdot 2\approx 1710\mathrm{to}Df$$

...

Power required to heat 450 kg of oil by 2 degrees in 1 minute (60 s)

. $$P=E/T=1710/60=28.5\mathrm{to}\mathrm{IN}t$$

...

The energy required to heat 450 kg of oil from minus 23 ° С to plus 50 ° С

. $$E=\mathrm{from}\cdot m\cdot \Delta t=1.9\cdot 450\cdot 73\approx 62415\mathrm{to}Df$$

...

Estimated warm-up time at input power P = 28.5 kW

$$T=E/P=62415/28.5=2190\mathrm{from}\approx 37m\mathrm{and}n...$$

Net pump power:

, $$N_n=P\cdot Q$$

,

where Np is the useful power of the pump, W

Р - working pressure, max 16 MPa,

Q - consumption, cbm / s

Pump drive speed n = 1600 rpm (with the gear ratio from the PTO shaft to the engine crankshaft equal to one).

, $$Q_n=n\cdot V_n$$

,

where n is the speed, rpm,

Vn - working volume, cc.

Q = 1600 100 = 160 000 cm3 / min = 160 l / min = 0.0026 m3 / s

Nп = 16 10 ⁶ 0.0026 = 41600 W = 41.6 kW

The pressure drop across the throttle is defined as:

Δp = Δt s C m,

where Δt is the increase in oil temperature,

с - oil density, 900 kg / m ³ ,

С - specific heat capacity, for oil 1.9 kJ / (kg K),

m - mechanical equivalent of heat (in SI m = 1)

Let us consider the calculation of the pressure loss when sequentially disconnecting the throttles when the corresponding Δt is reached in the temperature range from -30 ° C to + 50 ° C

Δp = ₁ · 80 · 900 1.9 · 1 = 119 700 kg / m ² ~ 1.2 MPa,

Δp = ₂ · 40 · 900 1.9 · 1 = 68400 kg / m ² ~ 0.7 MPa,

Δp ₃ = 20 900 1.9 1 = 34200 kg / m ² ~ 0.3 MPa.

Choke power loss is defined as:

ΔN = Δp Q

ΔN ₁ = 1.2 10 ⁶ 0.0026 = 3120 W ~ 3.1 kW,

ΔN ₂ = 0.7 10 ⁶ 0.0026 = 1820 W ~ 1.8 kW,

ΔN ₃ = 0.3 10 ⁶ 0.0026 = 780 W ~ 0.8 kW.

Taking into account the fact that this system uses three chokes, then the losses ΔN are added to the calculated power required to heat 450 kg of oil.

$$N_{\mathrm{about}bu}=P+{\displaystyle \sum \Delta N}$$

$$N_{\mathrm{about}bu}=28.5+3.1+1.8+0.8=34.2\mathrm{to}\mathrm{IN}t$$

Thus, the useful power of the pump, taking into account losses, is sufficient to ensure the specified parameters of the heating rate.

The calculated data were confirmed experimentally during the factory and state tests of the prototype ATMZ-7-65224.

The prototype ATMZ-7-65224 in the course of state tests on the basis of the Federal State Budgetary Institution "3 Central Research Institute" of the Ministry of Defense of Russia underwent an assessment of performance in conditions and after exposure to climatic environmental factors, namely exposure at a temperature of -50 ° C for 12 hours, at the request of the customer ... After twelve-hour exposure at minus 50 ° C, the oil temperature in the oil tank was minus 23 ° C. The warm-up time to plus 50 ° С was 43 minutes, which is consistent with the calculated data with an acceptable error.

Upon reaching the required temperature (maximum plus 50 ° C), the throttle assembly is turned off. Further, the necessary operations are carried out, for example, through the lines 8 and 9 and the unit 12, the pump 10 can deliver oil to external consumers. Pump 10 and throttle 14 can be used as an additional stage for oil heating. Hydraulic motor 1 can be used to drive the fuel pump (if the declared device is installed on an auto fuel and oil dispenser), which saves on maintenance of the hydraulic drive, because oil is constantly being updated and reduces the range of used fuels and lubricants. It is also possible to heat up a third-party tank, if you connect the declared device to the corresponding external heat exchanger, that is, start the oil circulation through this heat exchanger.

Claims (3)

1. A device for converting mechanical energy of oil into heat, containing an oil tank, pressure and drain lines, a pump installed in parallel in the pressure line, throttles and a hydraulic valve, characterized in that at least three chokes are installed, and the valve is made with the possibility of sequentially disconnecting the chokes depending on oil pressure. 2. The device according to claim. 1, characterized in that the pump is driven from the power take-off box of the engine of a specialized vehicle. 3. A device according to claim 1 or 2, characterized in that it contains additional drain and pressure lines with a pump and a hydraulic distributor made with the possibility of directing the oil flow for delivery to an external consumer, to the hydraulic motor and to the oil tank through an additional throttle.

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