Description:FORM – 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
[See section 10, Rule 13]

A DISTRIBUTOR CIRCUIT OF A REFRIGERATION UNIT FOR A FLUID REFRIGERANT FLOWING THERETHROUGH

BLUE STAR LIMITED A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS BLUE STAR LIMITED, BLUE STAR INNOVATION CENTRE, NEXT TO VIHANG’S INN HOTEL, KAPURBAVDI, GHODBUNDER ROAD, THANE WEST – 400 607, MAHARASHTRA, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
A DISTRIBUTOR CIRCUIT OF A REFRIGERATION UNIT FOR A FLUID REFRIGERANT FLOWING THERETHROUGH

FIELD OF THE INVENTION
The present disclosure relates to a distributor circuit of a refrigeration unit for a fluid refrigerant flowing therethrough.

BACKGROUND OF THE INVENTION
Generally, a heat pump, of an air-to-air type or an air-to-water type, works by extracting heat energy from outside air for use within a heating system. The heat pump consists of an outdoor heat exchanger unit to facilitate the extraction of heat energy from the outside air. The design of the outdoor heat exchanger unit plays an important role in the heat pumps running during a heating cycle. The outdoor heat exchanger unit consists of an outdoor coil. The outdoor coil has a plurality of outlets. During the heating cycle, the outdoor coil acts as an evaporator.
In the outdoor coil, either a header assembly or a normal distributor assembly is used. In the header assembly the refrigerant is distributed to multiple outlets arranged vertically on top of one another. It is necessary to have a uniform distribution of the refrigerant along all outlets of the coil during the heating cycle, to ensure uniform heat exchange takes place throughout the outdoor coil. When the header assembly is used, the flow of refrigerant through the outlets is non-uniform since the flow is against gravity. The flow in the topmost outlet is minimum whereas the flow in the bottom most outlet is maximum. This affects the heating capacity of the heat pump.
FIG. 1 illustrates a front view of a normal distributor assembly (100) for an air-to-air or an air-to-water heat pump. The normal distributor assembly (100) has a connector (102) connected to a plurality of outlet pipes (104). The normal distributor assembly (100) consists of four outlet pipes (104). The normal distributor assembly (100) has a L-pipe (106) to transfer a refrigerant from an expander (108) to the connector (102). The L-pipe (106) has a plurality of bends (110). The refrigerant from the expander (108) flows into the L-pipe (106) with a turbulent flow.
As illustrated in FIG. 2, when the refrigerant passes through the bend (110) of the L-pipe (106), a separation zone (112) is formed. The separation zone (112) is the detachment of a boundary layer from a surface into a wake. The wake is a region of disturbed fluid flow including eddies. Further, the eddy formation is a swirling of fluid and a reverse current creation when a fluid is in turbulent flow regime. The separation zone (112) causes resistance to the flow of refrigerant through the L-pipe (106). The resistance caused by the separation zone (112) stops the turbulent flow of the refrigerant from being fully developed along the bend (110) of the L-pipe (106). A ‘fully developed’ flow is a type of fluid flow in which the rate of change of all mean quantities (except pressure) with respect to the coordinate in the flow direction remains zero. The formation of a fully developed flow ensures equal distribution of refrigerant through the outlet pipes (104). It is necessary to have a uniform distribution of the refrigerant along all outlet pipes (104) during the heating cycle.
When the flow is not fully developed, the distribution of the refrigerant through the different outlet pipes (104) is non-uniform and this causes non-uniform fluid flow rate of the refrigerant, thus, non-uniform heat exchange. Further, low fluid flow rate of refrigerant in a particular outlet pipe (104) affects the frost formation in that outlet pipe (104). The non-uniformity in frost formation causes significant problems during the heat pump operation such as, affecting the defrost cycle and a low heating capacity.
Therefore, there is a need for a more efficient distributor which uniformly distributes the refrigerant through the outlets of the circuit with a uniform fluid flow rate and a fully developed turbulent flow.

SUMMARY OF THE INVENTION
In one embodiment of the present disclosure, a distributor circuit for a fluid refrigerant flowing therethrough is provided. The distributor circuit includes a plurality of outlet pipes. The distributor circuit also includes an inverted T-joint. The inverted T-joint has a horizontal pipe. The horizontal pipe has an inlet at one end and another end opposite to the inlet is closed. The inverted T-joint also has a vertical pipe. At one end, the vertical pipe is integrally connected to the horizontal pipe between the two ends of the horizontal pipe, thereby, forming a junction. Another end of the vertical pipe is connected to the outlet pipes in such a manner that the T-joint and the outlet pipes are in fluid communication. The horizontal pipe of the T-joint forms a fluid reservoir proximate the closed end of the horizontal pipe and a diameter of the horizontal pipe is greater than a diameter of the vertical pipe in such a manner that the fluid refrigerant flowing therethrough has a turbulent flow along with a fully developed fluid flow region and an equal fluid flow rate in all directions.
According to the present invention, a ratio of the diameter of the vertical pipe to the diameter of the horizontal pipe is between a range of 0.6 to 0.7.
According to the present invention, the junction and the closed end of the horizontal pipe are at a distance between a range of 50 millimetre to 52 millimetre.
According to the present invention, the distributor circuit is used in an air-to-air heat pump or air-to-water heat pump.

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a schematic view of a conventional distributor assembly;
FIG. 2 illustrates a schematic view of a bend associated with the conventional distributor assembly of FIG. 1;
FIG. 3 illustrates a schematic view of a distributor circuit, according to the present disclosure.
FIG. 4 illustrates a front view of a T-joint of the distributor circuit, according to the present disclosure;
FIG. 5a illustrates a top view of a horizontal pipe of the T-joint, according to the present disclosure;
FIG. 5b illustrates a front view of the horizontal pipe of the T-joint, according to the present disclosure;
FIG. 6 illustrates a front view of a vertical pipe of the T-joint, according to the present disclosure; and
FIG. 7 illustrates a schematic view of a plurality of fluid refrigerant flow regions through the T-joint, according to the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawings.
Embodiments are provided to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth relating to specific components to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
References in the present disclosure to “one embodiment” or “an embodiment” mean that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in an embodiment” or “in an implementation” in various places in the specification are not necessarily all referring to the same embodiment or implementation.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms “comprises,” “comprising,” “consists,” “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated elements, modules, units and/or components, but do not forbid the presence or addition of one or more other elements, components, and/or groups thereof.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
A fully developed fluid flow region is a region of fluid flow in which the rate of change of all mean quantities (except pressure) with respect to the coordinate in the flow direction remains zero.
Irrotational flow is a flow in which no element of a moving fluid rotates in any direction from one instant to the next.
Boundary layer region is defined as the region of a larger flow field that is next to a surface and has significant effects of wall frictional forces.
FIG. 3 illustrates a front view of a distributor circuit (200) of a refrigeration unit (not shown) for an air-to-air or an air-to-water heat pump, according to the present invention. The distributor circuit (200) includes a plurality of outlet pipes (202), a connector (203), and an inverted T-joint (204). The present disclosure consists of four outlet pipes (202). It should be noted that the distributor circuit (200) may include any number of outlet pipes (202) without limiting the scope of the present disclosure.
FIGS. 4, 5a, 5b, and 6 illustrate the T-joint (204) and its parts, according to the present disclosure. The T-joint (204) includes a horizontal pipe (206) and a vertical pipe (208). The horizontal pipe (206) has a first diameter (D1). The horizontal pipe (206) has an inlet (210) at one end (212). Another end (214) of the horizontal pipe (206) opposite to the inlet (210) is closed. The vertical pipe (208) has a second diameter (D2). The first diameter (D1) of the horizontal pipe (206) is greater than the second diameter (D2) of the vertical pipe (208) of the T-joint (204) in such a manner that a fluid refrigerant flowing therethrough has a turbulent flow. Further, a ratio of the diameter (D2) of the vertical pipe to the diameter (D1) of the horizontal pipe (206) lies between a range of 0.6 to 0.7. More specifically, the ratio of the second diameter (D2) to the first diameter (D1) lies between a range of 0.6 to 0.7. Further, the ratio of the second diameter (D2) to the first diameter (D1) may include value of 0.6 and 0.7. At one end (216) the vertical pipe (208) is integrally connected to the horizontal pipe (206) of the T-joint (204) between the two ends (212, 214) of the horizontal pipe (206), thereby, forming a junction (218). In the illustrated embodiment, a distance of the junction (218) from the closed end (214) of the horizontal pipe (206) lies between a range of 50 millimetre to 52 millimetre. In another embodiment, the distance of the junction (218) from the closed end (214) of the horizontal pipe (206) may include any other value as per the dimension of other components, without limiting the scope of the present disclosure. Another end (220) of the vertical pipe (208) is connected to the outlet pipes (202) in such a manner that the T-joint (204) and outlet pipes (202) are in fluid communication.
The inlet (210) has a smaller diameter than the horizontal pipe (206). The difference in the diameter of the inlet (210) and the horizontal pipe (206) reduces the speed of refrigerant flowing through the horizontal pipe (206). The reduction of speed is caused as cross-sectional area through which a fluid flows is inversely proportional to a velocity of the fluid flowing therethrough. The relation between the cross-sectional area and the velocity of the fluid is known from the equation of continuity.
The closed end (214) of the horizontal pipe (206) acts as a fluid reservoir. A fluid reservoir provides a release for a sudden rise in pressure and provides adequate flow of a fluid during a sudden drop in pressure. The closed section (214) of the horizontal pipe (206) ensures that the flow of the refrigerant through the T-joint is always turbulent.
The refrigerant used is (difluoromethane) R32. The flow characteristics of the refrigerant through the distributor circuit are found based on the Reynolds number. The formula for calculating the Reynolds number is as follows:
Re=(Inertial forces)/(Viscous forces)=(V_avg D)/( v)=(?V_avg D)/µ
Where,
? = Density of the fluid
µ = Dynamic viscosity of the fluid
D = Diameter of the passage way
v = kinematic viscosity of the fluid
Vavg = Average velocity of fluid (Vavg depends on the RPS (rounds per second) of the compressor.)
When the Reynolds number is greater than 3500 the flow is said to be turbulent. When the Reynolds number is greater than 4000 the flow is said to be fully turbulent.
As illustrated in FIG. 7 when a fluid with a fully turbulent flow enters a pipe, a length covered by the fluid before being fully developed is called a hydrodynamic entrance region (‘A’) of the pipe. The hydrodynamic entrance region refers to the area of a pipe where a fluid entering a pipe develops a velocity profile due to viscous forces propagating from the interior wall of the pipe. The hydrodynamic entrance region (‘A’) is further divided into a irrotational flow region (‘B’) and a velocity boundary layer (‘C’). In the irrotational flow region (‘B’) the viscous effects and velocity changes are negligible. In the velocity boundary layer (‘C’) a viscous shear force is significant. When the fluid enters the pipe, the thickness of the boundary layer (‘C’) gradually increases from zero moving in the direction of fluid flow. When the boundary layer’s edge (‘G’) reaches the pipe’s centerline, the flow becomes fully developed. The fluid (refrigerant) exits the hydrodynamic entrance region (‘A’) with a developing velocity profile (‘D’). When the flow of the refrigerant is fully developed (‘E’) and continues unchanged, the region of the pipe is called a fully developed fluid flow region (‘F’).
For an exemplary embodiment of the present disclosure, the dimensions and values are as follows:
Density of the refrigerant used (R32) = 961 kg/m^3
Dynamic viscosity of the refrigerant (R32) = 0.116 mPa.s
For lowest allowable compressor RPS,
Vavg = 3.29 m/s
Diameter of the horizontal pipe of the T-joint (D1) = 9.52 mm
Diameter of the vetical pipe of the T-joint (D2) = 6.35 mm
Diameter of the inlet on the horizontal pipe = 7 mm
Distance of the junction from inlet of the horizontal pipe = 97.5 mm
Distance of the junction from the closed end of the horizontal pipe = 50.6 mm
Length of the horizontal pipe = 120.6 mm
Length of the vertical pipe = 57 mm
Length of the connector = 8 mm
Substituting the dimensions and values of the present disclosure in the formula for calculating the Reynolds number
Re=(Integral forces)/(Viscous forces)=(V_avg D)/( v)=(?V_avg D)/µ
The result of the substitution provides a Reynolds number value of 252378.
The obtained value for the Reynolds number is greater than 4000. The flow characteristic of the refrigerant is fully turbulent flow.
The length of the hydrodynamic entry region required for a fully developed velocity profile to form is given by the following formula.
L_(h,turbulent)˜10D
Where,
L_(h,turbulent) = The length of the hydrodynamic entry region
D = diameter of the flow passage.
Substituting the diameter of the horizontal pipe, the length needed for formation of the fully developed velocity profile is 95.2 mm. The length of the bottom pipe is 120.6 mm according to the exemplary embodiment. The length of the bottom pipe is sufficient for formation of a fully developed velocity profile.
Substituting the diameter of the vertical pipe, the length needed for formation of the fully developed velocity profile is 63.5 mm. The length of the vertical pipe is 57 mm. The vertical pipe is connected to the outlet pipes through the connector. The total length of the vertical portion including the connector is 65 mm. The length of the vertical pipe is sufficient for the formation of a fully developed velocity profile.
The formula of Reynolds number for a compressor having a fixed RPS, with flow rate constant (Q) is written as
Re=(4.?.Q)/(µ.D)
The above equation explains that when the diameter of the vertical pipe is reduced, a surge is obtained in the turbulent flow at the entry of the connector. The surge at the entry of the connector ensures equal distribution of fluid flow in all the outlets.
The present invention ensures the flow of the refrigerant from the T-joint to the outlet pipes always remains turbulent. The present invention enables the fluid flow region of the refrigerant to be fully developed. The fully developed flow of the refrigerant ensures the refrigerant has a uniform fluid flow rate and an even distribution through all the outlets of the distributor circuit. The uniform fluid flow rate of the refrigerant through the outlets of the distributor enables a uniform heat exchange throughout the circuit which ensures uniform frost formation. The uniform frost formation ensures the heating capacity of the heat pump is not lowered.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
Any discussion of devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
, Claims:
1. A distributor circuit (200) of a refrigeration unit for a fluid refrigerant flowing therethrough, the distributor circuit (200) comprising:
a plurality of outlet pipes (204); and
an inverted T-joint (204) having:
a horizontal pipe (206) having an inlet (210) at one end (212) and closed end (214) opposite to the inlet (210); and
a vertical pipe (208),
wherein:
at one end (220), the vertical pipe (208) is integrally connected to the horizontal pipe (206) between the two ends (212, 214) of the horizontal pipe (206), thereby forming a junction (218), another end (220) of the vertical pipe (208) is connected to the outlet pipes (204) in such a manner that the T-joint (204) and the outlet pipes (204) are in fluid communication, and
the horizontal pipe (206) of the T-joint (204) forming a fluid reservoir proximate the closed end (214) of the horizontal pipe (206), a diameter (D1) of the horizontal pipe (206) is greater than a diameter (D2) of the vertical pipe (208) in such a manner that the fluid refrigerant flowing therethrough has a turbulent flow along with a fully developed fluid flow region (F) and an equal fluid flow rate in all directions.
2. The distributor circuit (200) as claimed in claim 1, wherein a ratio of the diameter (D2) of the vertical pipe (208) to the diameter (D1) of the horizontal pipe (206) is between a range of 0.6 to 0.7.
3. The distributor circuit (200) as claimed in claim 1 or claim 2, wherein the junction (218) and the closed end of the horizontal pipe (206) are at a distance between a range of 50 millimetre to 52 millimetre.
4. The distributor circuit (200) as claimed in any one of claims 1 to 3, wherein the distributor circuit (200) is used in an air-to-air heat pump or air-to-water heat pump.