Circuit with double-stage throttling by capillary tubes and with receiver
FIELD: heating; refrigerating or freezing plants.
SUBSTANCE: closed refrigerating circuit comprises compressor (1), condenser (2), evaporator (4), receiver (9), capillary tube (8) between condenser and receiver, capillary tube (10) between receiver and evaporator and thermal contact (11) between suction pipeline and receiver. Suction pipeline is oriented so that sucked gas passes through receiver from its lower part to upper part. Cooling agent in receiver flows from its upper part to lower part. There is thermal contact (12) between suction pipeline and capillary tube (8), which connects condenser and receiver.
EFFECT: superheating of sucked gas, prevention of water condensation in suction pipeline and increased efficiency factor.
2 cl, 3 dwg
The present invention relates to the cooling scheme described in the restrictive part of paragraph 1 of the claims. This scheme is designed to regulate the flow of refrigerant from the receiver to the evaporator through a pressure in the receiver and so that was the flooding of the evaporator.
Schemes of this type are known from many patent applications. In all these known approaches use direct stream in the heat exchanger. Due to the direct flow of the outlet temperature of these objects are committed to the total temperature, and this means that the exchanger can cool the receiver to a temperature close to the temperature of the evaporator, causing boiling of the refrigerant when it is throttling in the evaporator. Boiling of the liquid in the capillary tube strongly influences the mass flow rate. Figure 3 shows a plot of the calculated mass flow rate through a capillary tube under the assumption that the refrigerant at the entrance it has a boiling temperature. From the graph it is seen that the mass flow rate increases with the pressure drop at a pressure drop of less than 5 Kelvin, but almost does not change when the differential pressure above 5 Kelvin. The schedule is designed for R134a refrigerant at the evaporator temperature -20°C, but the same trend is observed for other temperatures of the evaporator and for other refrigerants such as R404a, R600a is R22. From this it follows that the ow cannot be regulated directly by changing the differential pressure, if the pressure differential is greater than 5 Kelvin, however, there are several ways to solve this problem, three of which are the following.
In the US 250045 pressure drop between the evaporator and the receiver is less than 5 Kelvin, and therefore the pressure drop can be used to regulate the flow, but a small temperature difference between the suction gas and receiver leads to two disadvantages. First, the heat exchange surface must be large, and secondly, even a small change in temperature causes a large change in mass flow, which creates a risk of resonance.
In the US 2871680 the suction pipe and the receiver form a heat exchanger with direct stream, coming from the bottom up. The problem with boiling of the refrigerant in the capillary tube is solved by separation of refrigerant in liquid and gas throttle and the subsequent expansion of these two components in separate capillary tubes.
The refrigerant enters the lower part of the receiver in the form of a throttle gas moves to its upper part, exchanging heat with the suction gas, and out through the capillary tube at the top of the receiver. Throttle gas when the throttle is only slightly boiling, and mass flow b the children grow with increasing pressure drop across the capillary tube. Part of the liquid under the action of gravity will fall to the bottom of the receiver and go from there through a separate capillary tube. The fluid throttling is boiling hard, and mass flow rate will be constant, as shown in figure 3.
This solution has two advantages: the flooded evaporator and the heat exchange surface can be small. Two factors reduce demands on the heat exchange surface: first, the large temperature difference at the heat exchanger and, secondly, from the receiver leaves a lot of gas by not uploading the heat exchanger.
This method has two shortcomings, one of which is that required additional capillary tube, and the second is that the flow control is limited due to the constancy of flow.
In DK 174179 this problem is solved by supercooling of the refrigerant immediately before its entrance into the capillary tube. Subcooling is accomplished using a separate heat exchanger, which transfers heat to the evaporator.
In this way there is no problem with the refrigerant in the capillary tube no matter how great the pressure difference between the evaporator and the receiver. However, one of the main objectives of this scheme is to ensure flooding of the evaporator, and this imposes a limitation on the amount of pressure drop that m is should be shown in the following way. The first step of throttling, from the condenser to the receiver, makes heat in the receiver, which increases the temperature and consequently the pressure. Suction gas carries away heat from the receiver and thereby reduces the temperature and pressure. The pressure and temperature in the receiver aim for a balance between input and exhaust heat, and the balance point is just the expression R1:
CP is the heat capacity of the refrigerant (index specified gaseous or liquid state),
RT - heat of vaporization,
Y - velocity of the refrigerant in the liquid state to the evaporator outlet.
Since the main purpose of the scheme is to maintain the evaporator is flooded, then Y will be positive. By substituting this condition in R1 R2 obtained:
The expression R2 sets an upper limit on what part of the total pressure drop can take place on the second throttling, in comparison with the first throttling because the pressure drop in the second throttling determines the temperature difference at the heat exchanger. It is important that this pressure drop was as much as possible to ensure as low as possible heat exchange surface.
According to the invention proposed a closed refrigeration circuit containing a compressor, a condenser, operitel is, receiver, capillary tube between the condenser and the receiver, the capillary tube between the receiver and the evaporator and thermal contact between the suction pipe and the receiver, and the suction pipe is oriented so that the intake gas passes through the receiver from its lower part to the upper part, and the refrigerant in the receiver flows from the top to the bottom.
Preferably, between the suction pipe and the capillary tube connecting the condenser and the receiver, there was thermal contact.
The invention differs from the above decisions by the presence of a counter flow heat exchanger. Suction gas passes into the receiver from its lower part to the upper and pereohlazhden refrigerant in the lower part of the receiver, with the result that he can pass the capillary tube without boiling.
According to the invention has a tubular receiver, continued at each end of the capillary tube. The refrigerant is throttled twice: first, on the way from the condenser to the top of the receiver, and then from the bottom of the receiver to the evaporator. The suction pipe is in thermal contact with the tubular receiver is oriented such that the intake gas passes from the lower part to the upper part, forming a heat exchanger with counter-flow. The liquid in the lower part of the receiver Pharaoh adatsa approximately to the temperature of the evaporator, and the intake gas is superheated to approximately the temperature of the receiver. When the balance between the input and exhaust of warmth is true the expression R3:
The main purpose of the scheme is to maintain a flooded evaporator, which means that Y is greater than zero. By substituting this condition in R3 we get R4:
The heat capacity of the liquid is always greater than the heat capacity of the gas. With this in mind, from R4 obtained R5:
The expression R5 is true always, and the evaporator will always be completely submerged without any limitation on the temperature in the receiver, in contrast to the scheme described in DK 174179, where there is a limit defined by R2. This means that the temperature in the receiver may be higher, and the heat exchanger surface is reduced accordingly.
Since the liquid in the lower part of the receiver pereohlajdenia, it is possible to throttle directly to the evaporator without further cooling, but it is important that the condition of the cooling fluid was performed. This condition occurs when the evaporator is flooded because of the flooding from it will flow the liquid refrigerant. Dependence R5 provides the fact that the evaporator is flooded at equilibrium, it is therefore important to ensure that flooding of the evaporator is going on the ILO to establish equilibrium. If the evaporator is located in its lower part, a large part of the refrigerant will accumulate in the evaporator when idle, and therefore, at start-up of the evaporator is to be submerged.
In a small home freezers and refrigerators as a throttling device is commonly used capillary tube with a thermal contact with the suction pipe, as shown in figure 1. In such construction occurs suction gas overheating, which gives two advantages: efficiency (coefficient of performance) increases (for most refrigerants), and warm the intake gas prevents the condensation of water on the suction pipeline, which otherwise might damage the freezers and refrigerators. When using the invention, the same advantages can be achieved by placing the first capillary tube in thermal contact with the suction pipe, as shown in figure 2 position 12.
Description of the drawings
1 schematically shows the diagram is usually used for small freezers and refrigerators. The schema contains the compressor (1), a condenser (2), a liquid conduit (3), an evaporator (4), the suction pipe (5), capillary tube (6), thermal contact (7) between the capillary tube and the suction pipeline.
Figure 2 schematically image is on the scheme according to the invention, different from the schema shown in figure 1, only the tubular receiver, which divides the capillary tube into two parts.
The scheme according to the invention contains a compressor (1), a condenser (2), a liquid conduit (3), an evaporator (4), the suction pipe (5), capillary tube (8), the receiver (9), capillary tube (10), thermal contact (11) between the receiver and the suction pipe, thermal contact (12) between the capillary tube and the suction pipeline.
Figure 3 shows a graph of calculated mass flow rate of refrigerant R134a capillary tube. The temperature at the outlet of the capillary tube is constant and equal to -20°C and the inlet temperature varies from -20°C to +25°C. Flowing the refrigerant has a boiling point.
The implementation of the invention:
The scheme according to the invention consists of four elements: the suction pipe, the tubular receiver and two capillary tubes. As an example presents the calculation of suitable size for freezers with a capacity of 100 Watts with compressor NLY9KK by Danfoss. The temperature in the receiver is equal to +10°C.
Technical data compressor NLY9KK have:
- Cooling effect at 30°C/-30°C (condenser/evaporator): 100 watts.
- Mass flow rate: 1,37 kg/h=0.34 g/s
Heat is transferred inlet pipe in three places:
1. From Kapil is Arnau tube:
Qcapill.=Flow·CFgas·20K=0.34 g/s·of 1.7 j/g/K·20K=12 watts
2. From condensation of gas in the upper part of the receiver:
Qgas=Flow·CFfluidly.·20K-Qcapill.=0.34 g/s·of 2.3 j/g/K·20 K-12 W=16 W-12 W=4 W
3. From the cooling of the fluid in the lower part of the receiver: Qfluidly.=Flow·CFfluidly.·40=0.34 g/s·of 2.3 j/g/K·40=31 watts
The heat exchanger can transfer the following amount of heat:
U - heat transfer coefficient,
A - surface heat transfer,
LMTD is the log mean temperature difference.
For tubular heat exchanger are:
dT1and dT2temperature difference at the inlet and outlet of the heat exchanger.
For simplicity, the temperature difference at the heat exchanger output here chosen equal to:
The bottleneck heat transfer is the inner surface of the suction pipe; and the minimum area of this surface is calculated by converting R6 to R7;
By substituting in R7 is possible to calculate the minimum surface thermal contact for these three locations on the suction line:
1. Along the capillary tube, see figure 2, item 12:
dT1=[20K·(1-CPgas/CPfluidly.)]=5,5 To Λ (dT2 =1K)⇒LMTD=(dT1-dT2)/ln(dT1/dT2)=4,5K/ln(5,5)=2,6
Andcapill.≥Qcapill./(U·LMTD)=12 W/(0.1 W/cm2/·2,6)=46 cm2
The length of the heat exchanger capillary tube must be at least
Lcapill.>46 cm2/1.5 cm=31 cm
2. Condensation in the upper part of the receiver:
Andcondens.≥Qcondens./(U·LMTD)=4 W/0.1 W/cm2/·10,6)=4 cm2
From this it follows that the contact of the suction pipe with the upper part of the receiver must be not less than:
Lthe top of Prien.>4 cm2/1.5 cm=3 cm
3. For hypothermia at the bottom of the receiver:
Andcondens.≥Qcondens./(U·LMTD)=31 W/0.1 W/cm2/·11)=28 cm2
and thus, the contact of the suction pipe to the bottom of the sink must be not less than:
Lthe bottom of Prien.>28 cm2/150 cm2/m=19 cm
Calculations show that:
1. Thermal contact between the capillary tube and the suction pipe should be not less than 31 cm2.
2. The contact between the receiver and the suction pipe must have a length of not less than (3 cm+19 cm)=22 see
When choosing a receiver 50 with the level of the refrigerant can be changed by 28 cm, and still satisfied the basic requirement, which is that the heat had at least 22 see If the diameter of the receiver is chosen equal to 22 mm, the volume of the refrigerant can be changed to 75 ml, which corresponds to 45 g of refrigerant. The constituent elements of the schema (see figure 2) will have the following dimensions:
- suction pipe (5): copper tube 6 mm × 120 cm;
receiver (9): 22 mm × 50 cm;
the first choke: capillary tube of 0.7 mm × 90 cm, with with a suction pipe thermal contact (12) length not less than 31 cm;
the second throttle: capillary tube (10) 0.7 mm × 90 cm
The invention provides an efficient and cheap controller as an alternative to the traditional throttling capillary tube used in small home freezers and refrigerators. The controller increases the efficiency of freezers and refrigerators and allows them to work better in terms of temperature change. For manufacturers of refrigerators will not be difficult to use the invention, as seen in figures 1 and 2, the only difference is a small receiver mounted in the middle of the capillary tube.
1. A closed refrigeration circuit containing the compressor (1), a condenser (2), an evaporator (4), a receiver (9), capillary tube (8) between the condenser and the receiver, to Villeroy tube (10) between the receiver and the evaporator and thermal contact (11) between the suction pipe and the receiver, moreover, the suction pipe is oriented so that the intake gas passes through the receiver from its lower part to the upper part, characterized in that the refrigerant in the receiver flows from the top to the bottom.
2. A closed refrigeration circuit according to claim 1, characterized in that between the suction pipe and the capillary tube (8)connecting the condenser and the receiver, there is a thermal contact (12).
FIELD: cooling equipment, particularly to control coolant flow.
SUBSTANCE: flow regulator is formed of capillary tubes serially connected one to another and having different inner diameters and lengths. The capillary tubes are arranged so that capillary tube having greater diameter is installed before one having lesser diameter in direction of coolant flow from cooling unit condenser.
EFFECT: increased efficiency of cooling unit operation in cooling and heat pump regimes, as well as simplified manufacturing and computation.
SUBSTANCE: invention refers to design of refrigerating equipment. The proposed method of absorption refrigerating apparatus operation consists in starting/tripping magnitude-constant thermal load on the generator unit of the absorption-diffusion refrigerating machine depending on the temperature. Thermal load starting/tripping is done depending on the temperature as measured at the elevation section of the absorption-diffusion refrigerating machine dephlegmator. Tripping is done at temperatures exceeding that of ammoniation. Starting is done at temperatures inferior or equal to that of ammoniation.
EFFECT: reduced energy consumption.
SUBSTANCE: present invention pertains to a cooling device. The cooling device has cooling circuit (9) comprising: i) compressor (2), executing the cooling cycle; ii) evaporator (3), absorbing heat energy of the medium being cooled; iii) condenser (4), transmitting heat energy to an external medium; iv) capillary pipe (5), allowing for expansion of the cooling agent coming out of condenser (4), and carrying the cooling agent to evaporator (3); v) valve (6) with electromagnetic control, controlling flow of the cooling agent and located between condenser (4) and capillary pipe (5); vi) bypass line (7), leveling pressure in the sucking and blowing parts of the compressor (2). The cooling circuit (9) also has: i) valve (16) electromagnetically controlled, which prevent reverse flow to evaporator (3) when compressor (2) is not working and which is in the sucking part of the compressor (2); ii) control mechanism (8), which delays opening of electromagnetically controlled valve (16) by a period, which runs from starting the compressor (2) until a limit value of torque is attained.
EFFECT: prevention of migration of cooling agent when the compressor is not working and easier start up of the compressor.
3 cl, 3 dwg
SUBSTANCE: present invention pertains to the power engineering industry. To extract heat from a cold medium and transmit it to a hot medium, heat of dissolution is used as well as separation from the solution, two or more substances or two or more groups of soluble or absorbable substances with different thermodynamic properties on their saturation lines or beyond these lines. For this purpose, in the cold part of the cycle, through a selective membrane or membrane, a solvent is moved from one solution to the other such that, one of the substances or one of the groups of substances separates from the solution or is absorbed, with heat release or heat absorption or no thermal effect. The second substance or group of substances is dissolved or separated by an absorber, with absorption of a large amount of heat. As a result, in the cold part of the cycle, heat is taken off the cooled medium. The obtained solution and separated substance or substances are channelled to the hot part of the cycle, heating them with oncoming heat exchanger. In the hot part of the cycle, there is oppositely directed movement of solvent through the selective membrane or membrane. As a result, a reverse thermal effect is achieved and heat is transferred to the hot medium. The obtained solution and separated substance are returned to the cold part of the cycle, cooling them with oncoming heat exchanger. Use of the invention increases efficiency of a refrigerator or heat pump.
EFFECT: increased efficiency of a refrigerator or heat pump.
FIELD: heating systems.
SUBSTANCE: invention refers to household appliances and can be used in absorption-diffusion cooling units. Operating method of absorption-diffusion cooling units consists in supplying lean solution from generator to absorber. Lean solution is supplied to absorber through distributor wherein the lean solution flowing down throughout the inner surface of distributor owing to wetting effect and gravitation forces flows around spreaders installed on inner surface of distributor, which leads to splitting of initial flow of lean solution into several individual flows. Flow characteristics of individual flows are proportional to the distributor inner surface area wetted by them. Individual flows are supplied to absorber which provides absorption process for each individual flow irrespective of the rest flows.
EFFECT: reducing daily energy consumption.
2 cl, 4 dwg
FIELD: heating systems.
SUBSTANCE: invention refers to cooling equipment, and namely to cooling plants and heat pumps, and can be used for cooling or heating the rooms and work environment. Steam ejector cooling plant consists of a condenser connected with one liquid pipeline through a throttle valve to evaporator, and with the other liquid pipeline through an intermediate vessel to steam generator. The latter is connected with steam pipeline to operating ejector nozzle, the inlet chamber of which is connected with a steam pipeline to evaporator, and diffuser is connected with a steam pipeline to condenser. Plant also consists of valves located on liquid pipelines connecting an intermediate vessel to condenser and steam generator. Plant is equipped with cyclic heating device of intermediate vessel or its part up to temperature exceeding steam generator temperature, and cyclic cooling device of intermediate vessel up to temperature not exceeding condenser temperature.
EFFECT: improving plant reliability and reducing plant specific consumption of materials.
16 cl, 2 dwg
SUBSTANCE: refrigerating unit for domestic cooling device includes leak-tight compressor and pre-compressor, oil cooler coil, condenser, connecting tube, evaporator and network of interconnected pipelines. Cylinder lid cooler is coupled with recuperative heat exchanger installed in oil reservoir of compressor. Inner pipeline of compressor functions as delivery coil linked with compressor cylinder at the inlet point, and with pre-compressor at the outlet point. Outlet nozzle of pre-compressor is connected to cylinder cooler.
EFFECT: increase of power efficiency and service life of domestic cooling device.
SUBSTANCE: at compressor station for gas conditioning before its delivery to gas-main pipeline which station contains gas-compressor plants including centrifugal boosters driven by gas-turbine engines, heat exchangers for gas cooling, pipelines and locking elements, in each of gas-compressor plants on one shaft and in one housing with centrifugal booster driven by gas-turbine engine, gas turboexpander, at that, outlet of gas cooling heat exchanger which inlet is connected with booster output is connected with inlet of gas turboexpander outlet of which is connected by pipeline with gas-main pipeline, at that, gas-compressor plants with gas turboexpander are collected in pairs in block-containers with possibility for each of gas-compressor plants of one block-container to work in parallel or in series.
EFFECT: gas-main pipelines reliability enhancement by means of supplying to them compressed air of reduced temperature.
SUBSTANCE: when natural gas is prepared for burning in boiler, temperature of natural gas at the outlet of expansion engine is provided by control of gas expansion extent so that it is below dew point temperature of heavy carbohydrate fractions - gas condensate. Gas is sent through separator for separation of gas condensate. At least part of natural gas without heavy fractions is sent through heat exchanger for cooling of natural gas burning products in boiler down to the temperature below dew point of water vapours, which are produced in process of natural gas burning, with preparation of water condensate. System for preparation of natural gas for supply to consumer contains at least one expansion engine and electric generator connected to its shaft, at least one gas separator, which is connected with its inlet to at least one outlet of gas from expansion engine, and also at least one gas heat exchanger, which is connected with its inlet to the outlet of at least one gas separator. Outlet of expansion engine is connected to the inlet of reservoir, volume of which is selected based on conditions of gas condensate discharge, and reservoir gas outlet is connected with inlet of gas separator. Outlets of reservoir and gas separator by liquid are connected with reservoir for collection of gas condensate, which is installed at the lower level, and outlet of separator by gas is connected to gas heat exchanger for cooling of burning products and with inlet of chill removal unit, which is connected to refrigerator, and outlets of gas heat exchanger and unit of chill removal by gas are connected to units of boiler gas collection units.
EFFECT: increase of chill use efficiency.
10 cl, 2 dwg
SUBSTANCE: essence of suggested method consists in the fact that before filling a booster with fuel components, thermal conditioning of spatial object and booster compartments is performed by ambient air compressed, dried, cooled or heated to required values of pressure, temperature and dew point temperature, and that before start to fill the booster with liquid hydrogen, liquid hydrogen is supplied into spatial object and booster compartments instead of air. At that, liquid hydrogen has the same values of pressure, temperature and dew point temperature providing required temperature-humidity conditions and neutral medium which ensures fire and explosion safety for launch facilities in the presence of hydrogen leak. The method is implemented by thermostating device which includes compressor for ambient air compression, filter, air coolers and electric air heater. Air cooling is performed in two flows of refrigerating medium supplied by pumps to air coolers from reservoirs, at that, refrigerating medium of the first flow has temperature 5 to 7°C and of the second flow - temperature -1 to -3°. Air heating is performed in the electric air heater, then the air is supplied to spatial object, manifold and further to booster compartments. Before starting to fill booster with liquid hydrogen, air supply is stopped and gaseous nitrogen supply starts. Gaseous nitrogen is obtained from liquid nitrogen stored in special reservoir by means of its gasification in gasifier and heating to required temperature in electric air heater.
EFFECT: increase of reliability, safety and improvement of operating characteristics in the launch preparation phase and during launch of carrier boosters.
5 cl, 2 dwg
FIELD: heating, ventilation.
SUBSTANCE: invention refers to the device and method to be used with air conditioning cycle. A turbine for power generation includes a rotor, a chamber and at least one nozzle for supply of a fluid medium to activate the rotor. Flow of the fluid medium out of the nozzle output is periodically interrupted with at least one device of the flow brake to increase fluid medium pressure inside the nozzle. In a thermo dynamic cycle two such turbines can be used; at that the first turbine is located after a compressor and before a heat exchanger, and the second turbine is located after an evaporator and before the compressor. The invention facilitates upgrading of a total efficiency owing to recuperation of a portion of energy.
EFFECT: upgraded efficiency of an air conditioning device.
31 cl, 14 dwg
FIELD: refrigerating engineering.
SUBSTANCE: proposed method includes setting the turbine outlet temperature and continuous measurement of pressure and temperature after air bleed stages of engine compressor. Air temperature and pressure at turbine inlet, temperature and pressure at turbine outlet and rotational speed of rotor are calculated by means of system modulating unit. Then, degree of reduction of pressure in turbine, present magnitude of corrected rotational speed of rotor and optimal magnitude of corrected rotational of rotor corresponding to maximum efficiency of turbine are determined. Braking torque of rotor is changed by acting on braking unit till optimal and present magnitudes of rotational speed of rotor get equal. In case rated magnitude of air temperature at turbine outlet exceeds preset magnitude, flow rate of purging air is decreased or increased till magnitudes get equal. When these temperatures are equal, consumption of fuel is determined for each bleed stage and is analyzed for obtaining minimum consumption of fuel. Then, air temperature and pressure at turbine inlet, temperature and pressure at turbine outlet and rotational speed of rotor are determined by means of sensors. According to results thus, obtained, above-mentioned parameters are determined and processes are repeated till optimal and present magnitudes of corrected rotational speed of turbine rotor and preset and measured magnitudes of air temperature at turbine outlet get equal after which actual consumption of fuel is determined.
EFFECT: reduced consumption of fuel.
6 cl, 1 dwg