US2008127661A1PendingUtilityA1
Evaporatively cooled condenser
Est. expiryDec 4, 2026(~0.4 yrs left)· nominal 20-yr term from priority
B21D 53/085F28D 5/02F28F 1/126F25B 2339/041F25B 49/027F28D 1/05383F25B 39/04F28F 13/187
40
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Claims
Abstract
A plurality of tubes define refrigerant passages extending vertically from a lower end to an upper end for condensing a superheated refrigerant to a subcooled liquid. A bottom header is in fluid communication with the lower end of the tubes, and a top header is in fluid communication with the upper end of the tubes. A plurality of fins extend back and forth between a plurality of apexes joined to the tubes by a connector with a plurality of gaps defined between the fins and the sides of the tubes to allow water to flow through the gaps for greater heat transfer. Methods of fabricating and a method of operating the heat exchanger are also described.
Claims
exact text as granted — not AI-modified1 . A heat exchanger assembly for a heating and ventilating and air conditioning system also including an evaporator and a compressor, said assembly comprising;
a plurality of tubes having an exterior surface and extending axially between a lower end and an upper end and spaced apart from one another to define a plurality of refrigerant passages, a bottom header in fluid communication with said lower ends of said tubes, a top header in fluid communication with said upper ends of said tubes, a plurality of fins extending back and forth between a plurality of apexes, a connector for joining said apexes of said fins to adjacent tubes, and said fins and adjacent tubes defining at least one gap therebetween for fluid communication axially along said exterior surface of said tubes.
2 . An assembly as set forth in claim 1 including a plurality of said gaps between said fins and said adjacent tubes.
3 . An assembly as set forth in claim 2 wherein said connector comprises a meld between said apexes of said fins and said adjacent tubes.
4 . An assembly as set forth in claim 3 wherein said connector comprises a brazed joint.
5 . An assembly as set forth in claim 3 wherein said fins include a plurality of notches extending inwardly from each of said apexes of said fins to define said plurality of gaps.
6 . An assembly as set forth in claim 2 wherein said apexes are spaced from said adjacent tubes and said connector comprises a plurality of bridges extending from said apexes to interconnect each apex to said adjacent tubes to define said gaps between said apexes and said bridges and said adjacent tubes.
7 . An assembly as set forth in claim 2 including a wicking coating lining said exterior surface of said tubes and extending through said gaps to wick a source of water through said gaps.
8 . An assembly as set forth in claim 7 wherein said wicking coating comprises a sintered metal coating having a porosity approximately between 40% and 60%.
9 . An assembly as set forth in claim 8 wherein said porosity is approximately 50%.
10 . An assembly as set forth in claim 7 wherein said wicking coating includes a plurality of sintered metal particles.
11 . An assembly as set forth in claim 10 wherein said wicking coating has a thickness of approximately between 3 to 5 times a diameter of said particles.
12 . An assembly as set forth in claim 10 wherein said sintered metal particles have a diameter of approximately between 70 microns and 90 microns.
13 . An assembly as set forth in claim 7 including a bottom water tank to provide the source of water to said wicking material.
14 . An assembly as set forth in claim 7 including a top water tank in fluid communication with said exterior surface of said upper ends of said tubes to provide the source of water to said wicking coating.
15 . An assembly as set forth in claim 14 including a plurality of valves each disposed at said upper end of each tube between said top water tank and said fins and movable between an open position and a closed position for controlling the flow of water from said top tank.
16 . An assembly as set forth in claim 15 including an actuator connected to said valves to selectively move said valves between said open and closed positions.
17 . An assembly as set forth in claim 16 including an actuator controller for controlling said actuator in response to a heat transfer rate {dot over (q)} and a latent heat of evaporation h fg of the water to determine the mass flow rate of water {dot over (m)} w flowing from the top water tank according to the equation
m
.
w
=
q
.
h
fg
.
18 . An assembly as set forth in claim 17 including a heat transfer calculator for advising said actuator controller of the heat transfer rate {dot over (q)} according to the equation {dot over (q)}={dot over (m)} r [λ g c pg (T ri −T s )+h fgr (1−λ g −λ f )+λ f c pf (T s −T ro )] wherein,
{dot over (m)} r is the mass flow rate of the refrigerant flowing through the plurality of refrigerant passages, T ri is the temperature of the refrigerant entering the plurality of refrigerant passages, T ro is the temperature of the refrigerant exiting the plurality of refrigerant passages, λ g is the fraction of the refrigerant passages where the heat extracted from the refrigerant cools the refrigerant from a superheated vapor, c pg is the specific heat of the refrigerant in a gaseous state, h fgr is the latent heat of evaporation of the refrigerant flowing through the plurality of refrigerant passages, λ f is the fraction of the refrigerant passages where the heat extracted from the refrigerant cools the refrigerant to a subcooled liquid, c pf is the specific heat of the refrigerant in a liquid state, and T s is the surface temperature of the tube.
19 . An assembly as set forth in claim 18 including a flow meter in communication with said heat transfer calculator for sensing the mass flow rate of refrigerant {dot over (m)} r through the refrigerant passages.
20 . An assembly as set forth in claim 18 including a mass flow calculator for advising said heat transfer calculator of the mass flow rate of refrigerant {dot over (m)}r through the refrigerant passages according to the equation
m
.
r
=
η
v
V
d
NP
suc
R
r
T
suc
wherein;
η v is a volumetric efficiency of said compressor,
V d is a displacement rate of said compressor,
N is a rotational speed of said compressor,
P suc is a suction pressure of said compressor,
T suc is a suction temperature of said compressor, and
R r is a gas constant of the refrigerant.
21 . An assembly as set forth in claim 20 including a pressure gauge for measuring the suction pressure of said compressor.
22 . An assembly as set forth in claim 20 including a temperature sensor for sensing the suction temperature of said compressor.
23 . An assembly as set forth in claim 16 including a blower for moving air transversely to said tubes.
24 . An assembly as set forth in claim 23 including a blower controller for controlling said blower in response to a mass flow rate of water {dot over (m)}w according to the equation
m
.
a
=
m
.
w
ω
o
-
ω
i
wherein {dot over (m)}w is the mass flow rate of water flowing from the top water tank and ω i is an incoming absolute humidity of the air entering the fins and ω o is an outgoing absolute humidity of the air exiting the fins.
25 . A heat exchanger assembly for a heating and ventilating and air conditioning system also including an evaporator and a compressor, said assembly comprising;
a plurality of tubes each having parallel sides spaced apart from one another and extending between a front closure and a back closure and longitudinally from a lower end to an upper end, a bottom header in fluid communication with said lower ends of said tubes, a top header in fluid communication with said upper ends of said tubes, said tubes including a plurality of internal dividers extending longitudinally to define a plurality of refrigerant passages in each tube for carrying refrigerant flowing between said bottom and top headers, a bottom water tank in fluid communication with said lower ends of said tubes for storing a supply of water to provide to said parallel sides of said tubes, a top water tank in fluid communication said upper ends of said tubes for supplementing the supply of water provided to said parallel sides of said tubes, a blower for moving air transversely to said tubes, a plurality of fins extending back and forth between a plurality of apexes and extending between said front closure and said back closure, a connector for joining said apexes of said fins to adjacent parallel sides, a sintered metal coating of approximately 50% porosity and a particle diameter of approximately between 70 microns to 90 microns and a thickness of approximately between 3 to 5 times said particle diameter to define a wicking coating on said parallel sides of said tubes for wicking water from said top and bottom water tanks to said parallel sides of said tubes by capillary action, said fins and adjacent tubes defining a plurality of gaps therebetween for fluid communication longitudinally along said parallel sides, said wicking coating extending through said gaps for wicking water from said top and bottom water tanks and along said parallel sides of said tubes, a plurality of valves each disposed at said upper ends of each tube between said top water tank and said fins and movable between an open position and a closed position for controlling the flow of water from said top water tank, an actuator connected to said valves to selectively move said valves between said open and closed positions, an actuator controller for controlling said actuator in response to a heat transfer rate {dot over (q)} and a latent heat of evaporation h fg of the water to determine the mass flow rate of water {dot over (m)}w flowing from said top water tank according to the equation
m
.
w
=
q
.
h
fg
,
a heat transfer calculator for advising said actuator controller of the heat transfer rate {dot over (q)} according to the equation {dot over (q)}={dot over (m)} r [λ g c pg (T ri −T s )+h fgr (1−λ g −λ f )+λ f c pf (T s −T ro )] wherein,
{dot over (m)}r is the mass flow rate of the refrigerant flowing through the plurality of refrigerant passages,
T ri is the temperature of the refrigerant entering the plurality of refrigerant passages,
T ro is the temperature of the refrigerant exiting the plurality of refrigerant passages,
λ g is the fraction of the refrigerant passages where the heat extracted from the refrigerant cools the refrigerant from a superheated vapor,
c pg is the specific heat of the refrigerant in a gaseous state,
h fgr is the latent heat of evaporation of the refrigerant flowing through the plurality of refrigerant passages,
λ f is the fraction of the refrigerant passages where the heat extracted from the refrigerant cools the refrigerant to a subcooled liquid,
c pf is the specific heat of the refrigerant in a liquid state,
T s is the surface temperature of the tube, and
a blower controller for controlling said blower in response to the mass flow rate of water {dot over (m)}w according to the equation
m
.
a
=
m
.
w
ω
o
-
ω
i
wherein ω i is an incoming absolute humidity of the air entering the fins and ω o is an outgoing absolute humidity of the air exiting the fins.
26 . An assembly as set forth in claim 25 wherein said connector comprises a meld between said apexes of said fins and said adjacent tubes.
27 . An assembly as set forth in claim 26 wherein said connector comprises a brazed joint.
28 . An assembly as set forth in claim 26 wherein said fins include a plurality of notches extending inwardly from each of said apexes of said fins to define said plurality of gaps.
29 . An assembly as set forth in claim 25 wherein said apexes are spaced from said adjacent tubes and said connector comprises a plurality of bridges extending from said apexes to interconnect each apex to said adjacent tubes to define said gaps between said apexes and said bridges and said adjacent tubes.
30 . An assembly as set forth in claim 25 including a flow meter in communication with said heat transfer calculator for sensing the mass flow rate of refrigerant {dot over (m)}r through the refrigerant passages.
31 . An assembly as set forth in claim 25 including a mass flow calculator for advising said heat transfer calculator of the mass flow rate of refrigerant {dot over (m)}r through the refrigerant passages according to the equation
m
.
r
=
η
v
V
d
NP
suc
R
r
T
suc
wherein;
η v is a volumetric efficiency of the compressor,
V d is a displacement rate of said compressor,
N is a rotational speed of said compressor,
P suc is a suction pressure of said compressor,
T suc is a suction temperature of said compressor, and
R r is a gas constant of the refrigerant.
32 . An assembly as set forth in claim 31 including a pressure gauge for measuring the suction pressure of said compressor.
33 . An assembly as set forth in claim 31 including a temperature sensor for sensing the suction temperature of said compressor.
34 . A method of fabricating a heat exchanger comprising;
spacing a plurality of tubes apart from one another to define a plurality of refrigerant passages each having an exterior surface and extending axially from a lower end to an upper end, securing a bottom header to the lower ends of the tubes in fluid communication with the refrigerant passages, securing a top header to the upper ends of the tubes in fluid communication with the refrigerant passages, placing a plurality of fins extending back and forth between a plurality of apexes between adjacent tubes, securing the fins to the adjacent tubes, and forming a plurality of gaps between the fins and the adjacent tubes for fluid communication axially along the exterior surface of the tubes.
35 . A method as set forth in claim 34 further including forming a bridge to connect each of the apexes across a portion of the gaps to maintain the gaps and to interconnect each apex to the adjacent tube.
36 . A method as set forth in claim 34 further including forming a wicking coating along an exterior surface of the tubes.
37 . A method as set forth in claim 36 further including extending the wicking coating through the gaps between the apexes and the adjacent tube.
38 . A method as set forth in claim 36 wherein the forming is further defined as forming a sintered metal coating along the tubes having a porosity approximately between 40% to 60%.
39 . A method as set forth in claim 38 wherein the forming is further defined as forming the sintered metal coating having a porosity of approximately 50%.
40 . A method as set forth in claim 36 wherein the forming is further defined as forming the wicking coating from a plurality of particles each having a diameter and layering the coating to a thickness of approximately between 3 to 5 times the diameter of the particles.
41 . A method as set forth in claim 36 wherein the forming is further defined as forming a plurality of particles each having a diameter approximately between 70 microns to 90 microns.
42 . A method as set forth in claim 36 further including securing a bottom water tank adjacent the lower ends of the tubes in fluid communication with the wicking coating.
43 . A method as set forth in claim 36 further including securing a top water tank adjacent the upper ends of the tubes in fluid communication with the wicking coating.
44 . A method as set forth in claim 43 further including securing a valve movable between an open position and a closed position at the upper ends of each of the tubes between the top water tank and the fins.
45 . A method as set forth in claim 44 further including securing an actuator to the valves to selectively move the valves between the open and closed positions.
46 . A method of operating a heat exchanger of the type including a plurality of tubes extending axially to define a plurality of refrigerant passages and a plurality of fins extending between adjacent tubes and extending back and forth between a plurality of apexes and a plurality of gaps defined between the fins and adjacent tubes for fluid communication axially along an exterior surface of the tubes, the method comprising;
flowing a refrigerant through the plurality of refrigerant passages, extracting heat from the refrigerant, transferring the extracted heat to a source of water to evaporate the water, and flowing the source of water along an exterior surface of the tubes and through the plurality of gaps.
47 . A method as set forth in claim 46 wherein the flowing is further defined as wicking water through the gaps.
48 . A method as set forth in claim 47 further defined as regulating the flow of the source of water to a wicking coating.
49 . A method as set forth in claim 48 wherein the regulating is according to the equation
m
.
w
=
q
.
h
fg
wherein {dot over (q)} is the rate at which heat is extracted from the refrigerant and h fg is the latent heat of evaporation of the water.
50 . A method as set forth in claim 49 further defined as determining the heat transfer rate {dot over (q)} according to the equation {dot over (q)}={dot over (m)} r [λ g c pg (T ri −T s )+h fgr (1−λ g −λ f )+λ f c pf (T s −T ro )] wherein;
{dot over (m)}r is the mass flow rate of the refrigerant flowing through the plurality of refrigerant passages, T ri is the temperature of the refrigerant entering the plurality of refrigerant passages, T ro is the temperature of the refrigerant exiting the plurality of refrigerant passages, λ g is the fraction of the refrigerant passages where the heat extracted from the refrigerant cools the refrigerant from a superheated vapor, c pg is the specific heat of the refrigerant in a gaseous state, h fgr is the latent heat of evaporation of the refrigerant flowing through the plurality of refrigerant passages, λ f is the fraction of the refrigerant passages where the heat extracted from the refrigerant cools the refrigerant to a subcooled liquid, c pf is the specific heat of the refrigerant in a liquid state, and T s is the surface temperature of the tube.
51 . A method as set forth in claim 50 further defined as obtaining the refrigerant mass flow rate {dot over (m)}r from a mass flow meter.
52 . A method as set forth in claim 50 further defined as determining the mass flow rate {dot over (m)}r of the refrigerant according to the equation
m
.
r
=
η
v
V
d
NP
suc
R
r
T
suc
wherein;
η v is a volumetric efficiency of the compressor,
V d is a displacement rate of the compressor,
N is a rotational speed of the compressor,
P suc is a suction pressure of the compressor,
T suc is a suction temperature of the compressor, and
R r is a refrigerant gas constant of the refrigerant.
53 . A method as set forth in claim 49 further defined as conveying air through the plurality of fins to carry the evaporated water away from the tubes.
54 . A method as set forth in claim 53 further defined as determining a mass flow rate {dot over (m)}a of the air according to the equation
m
.
a
=
m
.
w
ω
o
-
ω
i
wherein ω i is an incoming absolute humidity of the air entering the fins and ω o is an outgoing absolute humidity of the air exiting the fins.
55 . A method as set forth in claim 54 further defined as providing a power input H fan to a blower according to the equation
H
fan
=
0.2414
g
c
(
1
η
fan
)
(
1
d
19
/
4
)
(
μ
a
1
/
4
ρ
a
)
m
.
a
wherein;
g c is the universal proportionality constant,
η fan is a blower efficiency,
d is a hydraulic diameter of an airflow passage of the blower,
μ a is a dynamic viscosity of the air, and
ρ a is a density of the air.Join the waitlist — get patent alerts
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