Apparatus, system, and method for heat exchange

Abstract

The present invention provides an apparatus for heat exchange, comprising a plurality of fins and a heat transfer coil in the form of a plurality of rectangular tubes arranged in a single array. The fins are arranged substantially vertically along longitudinal portions of the rectangular tubes. The rectangular tubes of the heat transfer coil each have a substantially rectangular cross-section with rounded edges, or an oval or elliptical cross-section, and the major axes of the rectangular tubes are operatively configured with an inclination angle to direct incoming convective fluid toward all of the rectangular tubes to effect heat exchange. Related systems and methods related to the apparatus are further described.

Description

[Technical Field]

[0001] The present invention claims priority to Singapore patent application no. 10202251384B, filed October 14, 2022, the disclosure of which is incorporated herein in its entirety.

[0002] The present invention relates to heat exchange techniques for passive displacement cooling. More particularly, the present invention relates to heat exchanger apparatus suitable for passive displacement cooling, and related systems and methods. [Background technology]

[0003] Passive displacement cooling involves influencing natural convective airflow within an indoor or enclosed environment to provide cooling. Such cooling may not require reliance on mechanically driven devices to constantly drive airflow within the indoor or enclosed environment. As such, systems implementing passive displacement cooling are well suited for on-demand and / or targeted cooling within indoor or enclosed environments.

[0004] However, widely adopted cooling means that perform passive displacement cooling continue to be considered to have slow response times and low cooling capacities due to their reliance on natural convective airflow, thus requiring long times to cool an indoor or enclosed environment.

[0005] Furthermore, current systems of heat exchangers that implement passive displacement cooling include alternative air-cooling heat exchanger arrangements that are operated in conjunction with mechanical fans to accommodate forced convection airflow, instead of those originally suited for active cooling. In other words, the use of such air-cooling heat exchanger arrangements is not suitable for passive displacement cooling because the cooling is achieved by low-velocity air, which requires different design parameters.

[0006] Furthermore, fans utilized in current systems for heat exchangers implementing passive displacement cooling have large areas that have proven excessive for low-velocity, natural passive convection, introducing unwanted viscous forces to the flow without significant downstream heat transfer. Coupled with a well-developed thermal boundary layer, the resulting low mass flow rate adversely affects cooling capacity and response time. This is exacerbated by condensation under cooling conditions. Retention of this condensation increases flow resistance to convective airflow.

[0007] Among the techniques disclosed in the prior art that may be relevant to an apparatus for a passive displacement cooling heat exchanger is the work disclosed in "Natural convection of plate finned tube heat exchangers with two horizontal tubes in a chimney: Experimental and numerical study, 2019" by Chen et al., which discloses an apparatus for heat exchange performed in a chimney. The apparatus includes a plate-finned heat transfer coil, which is in the form of a tube with a circular cross section.

[0008] Yet another related prior art disclosure includes the work by Unger et al., "Numerical optimization of a finned tube bundle heat exchanger arrangement for passive spent fuel pool cooling to ambient air, 2020," which discloses an apparatus for heat exchange in passive cooling of spent fuel assemblies. The apparatus includes finned bundled heat transfer coils in the form of tubes with various cross sections, arranged in an in-line or staggered configuration with vertical ducts at the tip tubes for cooling fluids.

[0009] However, the aforementioned prior art techniques still face the above-mentioned challenges when implementing passive replacement cooling. Therefore, it would be desirable to have a heat exchange apparatus, system, and corresponding method that is suitable and optimized for natural convection airflow for passive replacement cooling and provides improved response time and cooling capacity for rapid cooling in indoor or enclosed environments. [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] "Natural convection of plate finned tube heat exchangers with two horizontal tubes in a chimney: Experimental and numerical study, 2019" by Chen et al. [Non-patent document 2] "Numerical optimization of a finned tube bundle heat exchanger arrangement for passive spent fuel pool cooling to ambient air," by Unger et al., 2020 Summary of the Invention

[0011] The present invention provides a heat exchange device, system, and corresponding method that favors and optimizes the natural convection airflow of passive displacement cooling. To this end, the present invention provides a heat exchange device that is a finned heat transfer coil. The coil is in the form of rectangular cross-section tubes arranged in a single array, either in a single column or a single row. Each rectangular cross-section tube has a substantially rectangular cross-section with rounded edges, or an oval or elliptical cross-section, and is inclined at an angle to the convection airflow induced by the fins of the heat transfer coil.

[0012] Advantageously, devices according to the present invention provide reduced viscous forces, thereby allowing for higher mass flow rates and heat transfer rates than conventional configurations, while enabling improved response times.

[0013] Also advantageously, the device of the present invention provides better condensation drainage due to the tube structure and configuration, thereby reducing the viscous effects of water retention, particularly on the fin surfaces.

[0014] Also advantageously, the device of the present invention provides a more compact design and better aesthetics for better fit with space constraints.

[0015] Also advantageously, the apparatus of the present invention allows for a reduction in the overall size of the tubing in the heat transfer coil, thereby allowing for lower material costs.

[0016] The present invention contemplates providing an apparatus for heat exchange comprising a plurality of fins and a heat transfer coil in the form of a plurality of rectangular tubes arranged in a single array, the fins being oriented substantially vertically along the longitudinal portions of the rectangular tubes to direct incoming convective fluid toward all of the rectangular tubes for effecting heat exchange.

[0017] Preferably, each of the rectangular cross-section tubes of the heat transfer coil has a substantially rectangular cross-section with rounded edges, or has an oval or elliptical cross-section.

[0018] Preferably, the rectangular cross-section tubes of the heat transfer coil are operatively configured with an inclination angle of the rectangular cross-section tubes such that they are inclined relative to the direction of the incoming convective fluid flowing through the heat transfer coil.

[0019] Preferably, the tilt angle is substantially in the range of 0 to 60°.

[0020] Preferably, the rectangular cross-section tube of the heat transfer coil has an aspect ratio substantially in the range of 2:1 to 5:1.

[0021] Preferably, each of the fins is formed with a plurality of holes to allow the rectangular cross-section tubes of the heat transfer coil to pass through.

[0022] The present invention further contemplates providing a system for heat exchange comprising an apparatus for heat exchange including a plurality of fins, a heat transfer coil in the form of a plurality of rectangular tubes arranged in a single array, and a duct housing the apparatus, the fins of the apparatus being positioned substantially along a longitudinal portion of the rectangular tubes to direct incoming convective fluid into the duct toward all of the rectangular tubes for effecting heat exchange with the outgoing convective fluid.

[0023] Preferably, each of the rectangular cross-section tubes of the heat transfer coil in the apparatus has a substantially rectangular cross-section with rounded edges, or has an oval or elliptical cross-section.

[0024] Preferably, the rectangular cross-section tubes of the heat transfer coils in the apparatus are operatively configured with an inclination angle of the rectangular cross-section tubes such that they are inclined relative to the direction of incoming convective fluid flowing through the heat transfer coils of the apparatus.

[0025] Preferably, the inclination angle of the tubes in the heat transfer coil is substantially in the range of 0 to 60°.

[0026] Preferably, the rectangular cross-section tube of the heat transfer coil in the present apparatus has an aspect ratio substantially in the range of 2:1 to 5:1.

[0027] Preferably, the fins of the device each have a plurality of holes formed therein to allow the rectangular cross-section tubes of the heat transfer coil to pass therethrough.

[0028] Preferably, the system further comprises a drip tray disposed below and adjacent the heat transfer coil for collecting condensation formed on the device.

[0029] Preferably, the duct includes horizontal and vertical portions, with bends that are substantially at right angles to each other.

[0030] Preferably, the device is located within a horizontal portion of the duct, adjacent to a vertical portion of the duct.

[0031] Preferably, the vertical portion of the duct has a length that extends from the vertical portion to a height below the horizontal portion.

[0032] The present invention also contemplates providing a method of heat exchange, comprising constructing an apparatus for heat exchange to include a plurality of fins and a heat transfer coil in the form of a plurality of rectangular cross-section tubes arranged in a single array, and constructing a duct to house the apparatus, wherein the fins of the apparatus are each disposed substantially vertically along a longitudinal portion of the rectangular cross-section tubes and direct incoming convective fluid to flow into the duct toward all of the rectangular cross-section tubes for effecting heat exchange with the outgoing convective fluid.

[0033] Preferably, the method further comprises the step of configuring each of the rectangular cross-section tubes of the heat transfer coil in the apparatus to have a substantially rectangular cross-section with rounded edges, or to have an oval or elliptical cross-section.

[0034] Preferably, the method further comprises the step of orienting the rectangular cross-section tube of the heat transfer coil in the apparatus at an inclination angle so that it is inclined relative to the direction of flow of the incoming convective fluid through the heat transfer coil.

[0035] Preferably, the method further comprises the step of collecting condensation formed on the device by means of a tray disposed adjacent to and below the device.

[0036] Those skilled in the art will readily appreciate that the present invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as the characteristics inherent therein. The embodiments described herein are not intended to limit the scope of the present invention.

[0037] To facilitate an understanding of the present invention, a preferred embodiment from the perspective of the reader is illustrated in the accompanying drawings. When considered in conjunction with the following description, the present invention, its structure, operation, and its many advantages will be readily understood and appreciated. [Brief explanation of the drawings]

[0038] [Figure 1] FIG. 1 illustrates a structure including at least one heat source and a system for heat exchange provided by the present invention that implements passive displacement cooling within the structure. [Figure 2] FIG. 2 is a cross-sectional perspective view of the system shown in FIG. 1. [Figure 3] 2 is a perspective view of an apparatus for heat exchange provided by the present invention within the system shown in FIG. 1. FIG. [Figure 4] 1 is a side cross-sectional view of a portion of a system for heat exchange, including an apparatus for heat exchange in a first example configuration, in which the rectangular cross-section tubes of the heat transfer coil are arranged in a single array, the rectangular cross-section tubes having substantially rectangular cross-sections with rounded edges, or having oval or elliptical cross-sections, and a substantially 0° tilt angle. [Figure 5] 1 is a side cross-sectional view of a portion of a system for heat exchange, including an apparatus for heat exchange in a second example configuration, in which the rectangular cross-section tubes of the heat transfer coil are arranged in a single array, the rectangular cross-section tubes having a substantially rectangular cross-section with rounded edges, or an oval or elliptical cross-section, and an inclination angle of substantially 30°. [Figure 6] 10 is a side cross-sectional view of a portion of a system for heat exchange, including an apparatus for heat exchange in a third example configuration, in which the rectangular cross-section tubes of the heat transfer coil are arranged in a single array, the rectangular cross-section tubes having a substantially rectangular cross-section with rounded edges, or an oval or elliptical cross-section, and at a substantially 45° inclination angle. [Figure 7]10 is a side cross-sectional view of a portion of a system for heat exchange, including an apparatus for heat exchange in a fourth example configuration, in which the rectangular cross-section tubes of the heat transfer coil are arranged in a single array, the rectangular cross-section tubes having a substantially rectangular cross-section with rounded edges, or an oval or elliptical cross-section, and an inclination angle of substantially 60°. [Figure 8] 1 is a graph illustrating the increase in perceptible heat transfer versus an increase in mass flow rate for one or more simulated system models of a heat transfer system. [Figure 9] FIG. 10 is a cross-sectional side view of a portion of a fin in an apparatus for heat exchange, further showing simulated air temperature contours across the channels of the fin. [Figure 10] 1 is a side cross-sectional view of a portion of a first system model simulated for heat exchange, further showing air temperature contours. The first system model includes an apparatus for heat exchange in which rectangular cross-section tubes of heat transfer coils are arranged in a single array, the rectangular cross-section tubes having substantially rectangular cross-sections with rounded edges, or having oval or elliptical cross-sections, and a substantially 0° tilt angle. [Figure 11] 1 is a side cross-sectional view of a portion of a simulated second system model for heat exchange, further showing air temperature contours. The second system model includes an apparatus for heat exchange in which rectangular cross-section tubes of heat transfer coils are arranged in a single array, the rectangular cross-section tubes having substantially rectangular cross-sections with rounded edges, or having oval or elliptical cross-sections, and a substantially 30° inclination angle. [Figure 12] 1 is a side cross-sectional view of a portion of a simulated third system model for heat exchange, further showing air temperature contours. The first system model includes an apparatus for heat exchange in which rectangular cross-section tubes of heat transfer coils are arranged in a single array, the rectangular cross-section tubes having substantially rectangular cross-sections with rounded edges, or having oval or elliptical cross-sections, and a substantially 45° inclination angle. [Figure 13]10 is a side cross-sectional view of a portion of a fourth system model simulated for heat exchange, further showing air temperature contours. The fourth system model includes an apparatus for heat exchange in which rectangular cross-section tubes of heat transfer coils are arranged in a single array, the rectangular cross-section tubes having substantially rectangular cross-sections with rounded edges, or having oval or elliptical cross-sections, and a substantially 60° inclination angle. [Figure 14] 10 is a cross-sectional side view of a portion of a simulated fifth system model for heat exchange, further showing air temperature contours. The fifth system model includes an apparatus for heat exchange in which the tubes of the heat transfer coil are arranged in a single array and have a circular cross section. [Figure 15] 10 is a cross-sectional side view of a portion of a sixth system model simulated for heat exchange, further showing air temperature contours. The sixth system model includes an apparatus for heat exchange in which the tubes of the heat transfer coil are arranged in two alternating rows and have a circular cross section. [Figure 16] 10 is a cross-sectional side view of a portion of a seventh system model simulated for heat exchange, further showing air temperature contours. The seventh system model includes an apparatus for heat exchange in which the tubes of the heat transfer coil are arranged in a two-row in-line configuration and have a circular cross section. [Figure 17] FIG. 10 is a cross-sectional side view of a first system model simulated for heat exchange, further illustrating velocity vectors. [Figure 18] FIG. 10 is a cross-sectional side view of a portion of a first system model simulated for heat exchange, further illustrating velocity vectors. [Figure 19] FIG. 10 is a cross-sectional side view of a second system model simulated for heat exchange, further illustrating velocity vectors. [Figure 20] FIG. 10 is a cross-sectional side view of a third system model simulated for heat exchange, further illustrating velocity vectors. [Figure 21] FIG. 10 is a cross-sectional side view of a fourth system model simulated for heat exchange, further illustrating velocity vectors. [Figure 22]FIG. 10 is a cross-sectional side view of a fifth system model simulated for heat exchange, further illustrating velocity vectors. DETAILED DESCRIPTION OF THE INVENTION

[0039] FIELD OF THE INVENTION The present invention relates to a heat exchanger apparatus suitable for passive displacement cooling, and related systems and methods.The present invention can be presented in several different embodiments with common elements.

[0040] According to the concept of the present invention, an apparatus for heat exchange includes a heat transfer coil having a plurality of rectangular tubes and a plurality of fins arranged along a longitudinal portion of the rectangular tubes through which the rectangular tubes pass. The rectangular tubes are arranged in a single array. Preferably, each rectangular tube has a substantially rectangular cross section with rounded edges, or an oval or elliptical cross section, and is inclined laterally at an oblique angle relative to the convective airflow induced by the fins. The above-described apparatus for heat exchange may further be implemented in related systems and methods for heat exchange.

[0041] The invention will now be described in more detail, by way of example, with reference to the figures in which: For ease of reference, a common reference number or a common series of numbers will be used in all figures when referring to the same or similar features that are common to the figures.

[0042] Figure 1 shows a structure 1 that includes at least one heat source 2 and an example of a system for heat exchange 3 that provides passive displacement cooling within the structure 1. Figure 2 is a cross-sectional perspective view of the system for heat exchange 3 provided by the present invention.

[0043] The structure 1 is preferably a closed structure, forming a substantially indoor or enclosed environment. The closed structure 1 may be defined as having one or more walls. It may be, for example, a room in a building. The structure 1 is furthermore a suitable space for forming and allowing a convective fluid flow therethrough.

[0044] Heat source 2 may preferably be a living organism or a non-living organism or occupant within structure 1. In particular, heat source 2 is a living organism or occupant that generates or dissipates heat as it performs biological activities within structure 1. Alternatively, heat source 2 is a non-living organism or occupant that generates or dissipates heat as it performs its intended function.

[0045] The system 3 for heat exchange includes at least a duct having a horizontal portion 311 and a vertical portion 312, a device 32 for heat exchange, and a tray 33. The system 3 promotes circulation of convective fluid flow within the structure 1, and the heat source 2 is located therein. Specifically, the system 3 receives hot air as an incoming convective fluid, cools it, and sends cool air to the heat source 2 as an outgoing convective fluid.

[0046] 1-2 further show that the horizontal portion 311 of the duct, the device 32, and the tray 33 are located at an elevated height within the structure 1, while the heat source 2 is located at floor level or below the elevated height within the structure 1. The vertical portion 312 of the duct extends from the elevated height to the floor. As such, the duct of the system 3 can be said to have an inverted L-shaped configuration, where a substantially right angle is formed between the horizontal portion 311 and the vertical portion 312.

[0047] 1-2 further illustrate that device 32 is housed substantially within horizontal portion 311 of the duct and disposed therein substantially adjacent and / or proximate to vertical portion 312 of the duct. More particularly, device 32 is substantially adjacent and / or proximate to the right angle formed between horizontal portion 311 and vertical portion 312 of the duct. Such a configuration prevents condensation formed in device 32 from entering vertical portion 312 of the duct.

[0048] 1 further shows that a drip pan 33 is disposed below the apparatus 32. The drip pan 33 collects and drains condensation that forms and drips from the apparatus 32, allowing it to drain for disposal or reuse.

[0049] FIG. 1 further illustrates the circulation of convective fluid flow within device 1, demonstrating the corresponding hot and cool air. Specifically, heat emitted or dispersed from heat source 2 heats the surrounding air, thereby creating warmer, lighter hot air. The hot air rises accordingly and enters system 3 through the inlet of horizontal duct section 311 as an incoming convective fluid. The hot air passes through device 32 for heat exchange, becoming cooler, denser cool air. The cool air exits device 32 as an outgoing convective fluid and proceeds toward vertical duct section 312. The cool air can be directed downward toward outlet 312a, which is located at the same height as heat source 2. Thus, the duct can be said to supply cool air. A pool of cool air forms near floor level. As the cool air displaces the hot air, a circulation of convective fluid flow occurs. The cooling effect occurs due to buoyancy forces generated by the difference in air density. In this way, the heat source 2 at floor level can be cooled.

[0050] 3 is a perspective view of an example of a heat exchanger 32 provided by the present invention, which may be a finned heat transfer coil. The apparatus includes a plurality of fins 321 and at least one heat transfer coil having a plurality of rectangular cross-section tubes 322, the cross-sectional shape of which may include a substantially rectangular cross-section with rounded edges, or an oval or elliptical cross-section. The description following FIG. 3 should be read with reference to the descriptions of FIGS. 1-2.

[0051] Preferably, the heat transfer coil provides cooling to the received convective fluid, and therefore the heat transfer coil may also be referred to as a "cooling coil."

[0052] The heat transfer coil may be configured with its rectangular cross-section tubes 322 in either a single pass, multiple tube configuration or a multiple pass, single tube configuration.

[0053] The fins 321 are preferably substantially flat, i.e., planar structures. Each fin 321 includes a longitudinal portion, which may correspond to the height axis of the fin. Each fin 321 includes lateral portions that are perpendicular to the longitudinal portion, which may correspond to the width axis of the fin.

[0054] The rectangular cross-section tubes 322 are preferably elongated structures having a substantially rectangular cross-section with rounded edges, or may have an oval or elliptical cross-section. Each rectangular cross-section tube 322 may include a longitudinal portion. The rectangular cross-section has a width or major axis. Each rectangular cross-section tube 322 may include lateral portions that are perpendicular to the longitudinal portion. The rectangular cross-section may have a height or minor axis. Each rectangular cross-section tube 322 may be formed with a major axis:minor axis ratio having an aspect ratio of substantially 2:1 to 5:1.

[0055] In particular, the fins 321 are arranged perpendicular to the rectangular cross-section tube 322 and each of them has a hole to allow a longitudinal portion of the rectangular cross-section tube 322 to pass through.

[0056] In particular, the fins 321 may be horizontally distributed along the longitudinal portion of the rectangular cross-section tube 322, spaced substantially equidistant from one another.

[0057] In particular, the fins 321 may be oriented along the longitudinal portion of the rectangular cross-section tube 322 such that their lateral portions are substantially perpendicular to the longitudinal portion of the rectangular cross-section tube 322 .

[0058] Specifically, the rectangular cross-section tubes 322 are arranged in a single array configuration and are distributed vertically along the height of the fin 321 so as to be substantially equidistant from one another. In this context, the term "single array" refers to an in-line arrangement of items forming a single row or a single column. Here, the rectangular cross-section tubes 322 are preferably in a single array configuration that allows them all to substantially receive the conductive fluid simultaneously or nearly simultaneously. Furthermore, because the rectangular cross-section tubes 322 are arranged in a single array configuration along the height of the fin 321, this arrangement may also be referred to as a "single row" arrangement.

[0059] Specifically, rectangular cross-section tubes 322 have a coolant flowing therethrough that flows along the length of rectangular cross-section tubes 322. Each end of rectangular cross-section tubes 322 may receive chilled or room temperature coolant, and the other end of each tube may discharge heated coolant. The coolant may be, by way of example, water or a fluid with a substantially specific heat capacity.

[0060] Specifically, the rectangular cross-section tubes 322 may be configured or set operatively with their longitudinal axes angled relative to the incoming convective fluid induced by the fins 321. This angle is hereinafter referred to as the "tilt angle." The tilt angle may be substantially between 0 and 60 degrees, with 0 to 30 degrees being most preferred. Thus, the fins 321 have holes that follow the tilt angle of the rectangular cross-section tubes 322.

[0061] Another interpretation of the tilt angle is that it can be defined as the angle defined between the width axis of the fin 321 and the width / long axis of the rectangular tube 322. Similarly, the tilt angle can be substantially between 0 and 60 degrees, but most preferably between 0 and 30 degrees. Thus, similarly, the fin 321 has holes that follow the tilt angle of the rectangular cross-section tube 322.

[0062] It should be noted that the length, width, and height axes of the fins 321 and the rectangular cross-section tube 322 are intended to be relative terms for reference and are not intended to be construed as limiting with respect to the relationship and orientation of the fins 321 and the rectangular cross-section tube 322. Additionally, the axes of the fins 321 and the rectangular cross-section tube 322 may be expressed in any other geometric system, such as a Cartesian coordinate system.

[0063] In particular, a heat transfer coil with a rectangular cross-section tube 322 having a substantially rectangular cross-section with rounded edges, or having an oval or elliptical cross-section, may allow the fins 321 to be shorter in terms of their width, length, and / or height. As such, the fins 321 may have a reduced surface area. In this way, the viscous forces experienced by the fins 321 may be reduced.

[0064] In particular, a heat transfer coil having a substantially rectangular cross-section with rounded edges, or having an oval or elliptical cross-section, and with multiple rectangular cross-section tubes 322 tilted at an oblique angle is more aerodynamically streamlined and induces less airflow resistance compared to a heat transfer coil with multiple tubes having circular cross-sections.

[0065] In particular, the heat transfer coil, having a substantially rectangular cross section with rounded edges, or having an oval or elliptical cross section, with multiple rectangular cross section tubes 322 inclined at an oblique angle, serves to remove condensation formed thereon, which further reduces airflow resistance.

[0066] FIG. 3 further illustrates the interaction of devices 32 within system 3 to perform the heat exchange.

[0067] Next, a method of heat exchange will be described. It should be noted that the steps described for this method should be construed as non-limiting, and minor changes to the steps (e.g., combination, addition, omission, or replacement) can be made by those skilled in the art without substantially departing from what has been described. Furthermore, all or some of the steps can be performed simultaneously or non-simultaneously.

[0068] In a first step, the device 32 is constructed having a plurality of fins 321 and a heat transfer coil in the form of a plurality of rectangular cross-section tubes 322 arranged in a single array. A duct is further constructed to house the device 32 in accordance with the above description.

[0069] In a second step, the apparatus 32 is configured so that each rectangular cross-section tube 322 of the heat transfer coil has a substantially rectangular cross-section with rounded edges, or has an oval or elliptical cross-section.

[0070] In a third step, the heat transfer coil rectangular cross-section tube 322 in the device 32 is configured to be oriented at an inclination angle that tilts the long axis relative to the intended direction of incoming convective fluid flow over the heat transfer coil rectangular cross-section tube 322. Preferably, the inclination angle is substantially in the range of 0 to 30 degrees.

[0071] In a fourth step, incoming convective fluid in the form of hot air is received at the inlet of the horizontal section 311 of the duct and moves towards the device 32 .

[0072] In a fifth step, the incoming convective fluid is then guided by the fins 321 of the device 32 and flows through the device 32 .

[0073] In a sixth step, the incoming convective fluid flowing through the device 32 encounters resistance from the rectangular cross-section tubes 322. The rectangular cross-section tubes 322, through which the coolant flows, absorb heat from the incoming convective fluid. In this manner, heat is exchanged between the incoming convective fluid and the coolant flowing within the rectangular cross-section tubes 322, and heat is transferred from the incoming convective fluid and the coolant flowing within the rectangular cross-section tubes 322. This causes the coolant to become heated. The heated coolant can then exit the device 32 and flow to a different heat exchange device for heat dissipation.

[0074] In the seventh step, as heat is transferred from the convective fluid to the coolant, condensation occurs within the device 32 in the form of droplets that form on one or both of the fins 321 and rectangular cross-section tubes 322.

[0075] Since the fins 321 are arranged perpendicular to the rectangular cross-section tube 322, condensation formed thereon can naturally flow by gravity and drip down towards the tray 33.

[0076] The rectangular cross-section tube 322 is preferably inclined at an inclination angle, so that condensation formed thereon can flow by gravity according to the inclination angle of the rectangular cross-section tube 322 and drip down towards the tray 33 .

[0077] This transfers heat from the incoming convection fluid to the coolant, cooling the incoming convection fluid, thus turning hot air into cool air.

[0078] In an eighth step, a tray 33 collects the condensation that drips onto it from the device 32 and is sent away for disposal or reuse.

[0079] Finally, in the ninth step, the cool air exits the device 32 as a convective fluid and flows towards the vertical section 312 of the duct before descending to floor level to reach the heat source 2 .

[0080] 4 to 7 show one or more example configurations of the device 32 for heat exchange in the system 3 for heat exchange.

[0081] 4 shows a side cross-section of a portion of the system 3 for heat exchange, including the device 32 for heat exchange in a first configuration example, in which the rectangular cross-section tubes 322 of the heat transfer coil are arranged in a single array, the rectangular cross-section tubes having a substantially rectangular cross-section with rounded edges, or an oval or elliptical cross-section, and the inclination angle is substantially 0°.

[0082] 5 shows a side cross section of a portion of a system 3 for heat exchange, including an apparatus 32 for heat exchange in a second example configuration in which rectangular cross-section tubes 322 of heat transfer coils are arranged in a single array, the rectangular cross-section tubes having a substantially rectangular cross-section with rounded edges, or an oval or elliptical cross-section, and an inclination angle of substantially 30°.

[0083] 6 shows a side cross section of a portion of a heat exchange system 3 including an apparatus for heat exchange 32 in a third example configuration in which the rectangular cross section tubes 322 of the heat transfer coil are arranged in a single array, the rectangular cross section tubes 322 having a substantially rectangular cross section with rounded edges or an oval or elliptical cross section, and the inclination angle is substantially 45°.

[0084] 7 shows a side cross section of a portion of a heat exchange system 3 including an apparatus for heat exchange 32 in a fourth example configuration in which the rectangular cross section tubes 322 of the heat transfer coil are arranged in a single array, the rectangular cross section tubes 322 having a substantially rectangular cross section with rounded edges or an oval or elliptical cross section, and the inclination angle is substantially 60°.

[0085] The following describes the evaluations that were performed to confirm the performance of the support structure. It should be noted that the parameters defined or determined in these evaluations are not meant to be construed as limiting the scope of the present invention.

[0086] One or more models were created and numerically analyzed using commercially available software, such as Ansys Fluent®, for example. Specifically, each system model was created to substantially resemble the cross-section of the system 3 for heat exchange, as shown in FIG.

[0087] A total of seven system models were created and simulations were performed on them.

[0088] The system models include a first system model called "1 row plane" based on a first configuration example shown in FIG. 4, a second system model called "1 row plane 30°" based on a second configuration example shown in FIG. 5, a third system model called "1 row plane 45°" based on a third configuration example shown in FIG. 6, and a fourth system model called "1 row plane 60°" based on a fourth configuration example in FIG. 7.

[0089] Further included are a fifth model having a configuration with one row of tubes with a circular cross section, designated "single row circular," a sixth model having a configuration with two rows of alternating tubes with circular cross sections, designated "two rows of circular (alternating)," and a seventh model having a configuration with two rows of in-line tubes with circular cross sections, designated "two rows of circular (in-line)."

[0090] For the evaluation, the impact of each system model configuration on mass flow rate and cooling capacity was investigated. Furthermore, their velocity vectors and their airflow temperature contours were evaluated.

[0091] Specifically, for evaluation, the tubes of the heat transfer coils of the first, second, third, and fourth models were fabricated to have an aspect ratio of the tube cross-sectional axis that was substantially 3:1.

[0092] In particular, for evaluation, the fin lengths and tube spacings in all system models were made according to standard heat transfer coil dimensions known in the art.

[0093] Specifically, for evaluation purposes, the tubes of the heat transfer coils in all system models were made to have the same heat transfer area.

[0094] Specifically, for evaluation purposes, the air temperature received by the simulated duct inlet in all system models was made constant.

[0095] In particular, for evaluation, all system models were constructed so that their ducts had a vertical section of substantially 800 mm height and a gap of substantially 100 mm.

[0096] In particular, for evaluation, all system models were constructed so that their ducts had a horizontal section with an inlet substantially 100 mm wide.

[0097] Specifically, for evaluation purposes, all system models can be made with their heat transfer coils substantially 305 mm high.

[0098] Specifically, for evaluation, the heat transfer coil tubes in all system models were fabricated to be substantially 50 inches (127 cm) long, or a total of 50 inches (127 cm) long.

[0099] Specifically, during evaluation, the fins of all system models were fabricated to have a density of substantially 10 FPI (fins per inch) and a channel gap of substantially 1.27 mm.

[0100] Simulations were performed for all seven system models for the half fin channel, and the results are shown in Table 1 below.

[0101] A graph of the increase in appreciable heat transfer versus increasing mass flow rate was constructed based on the results shown in Table 1 and is shown in FIG.

[0102] Note that the sixth system model is the baseline against which all other system models are compared.

[0103] [Table 1]

[0104] As shown in Table 1, the results show that for the system models having a coil with a rectangular cross-section flat tube with rounded edges (i.e., the first to fourth system models), the first system model has the highest mass flow rate m and appreciable heat transfer Q. a and a second system model has the second largest mass flow rate m and appreciable heat transfer Q a It means that it has.

[0105] As shown in Table 1, the results indicate that the system models having coils with a single array of "one row" tubes (i.e., System Models 1 to 5) have better mass flow rates m and cooling capacities compared to the system models having coils with multiple arrays of "two rows" tubes (i.e., System Models 6 and 7).

[0106] As shown in Table 1, comparing the sixth system model with the first system model, the first model increases the mass flow rate m by substantially 36.1%, from substantially 0.061 kg / s to substantially 0.083 kg / s, compared to the sixth system model. Furthermore, the first system model has a significant decrease in the heat transfer Q a In this case, the power consumption increases from substantially 1044.1 W to substantially 1316.5 W, a substantial increase of 26.1%.

[0107] As shown in Table 1, comparing the sixth system model with the second system model, the first model has a substantial 34.4% increase in mass flow rate m compared to the sixth system model, from substantially 0.061 kg / s to substantially 0.082 kg / s. Furthermore, the second system model has a significant decrease in the heat transfer Q a In this case, the power consumption increases from substantially 1044.1 W to substantially 1302.9 W.

[0108] Thus, performance improvements in the heat exchange device constructed according to either the first or second system model are evident, which are attributable to factors including (i) reduced viscous forces resulting from shorter fin lengths / widths / heights and reduced row lengths / widths / heights, and (ii) flat tubes with a more streamlined design compared to circular tubes.

[0109] As shown in Figure 9, the thermal boundary layers within the fins coalesce before leaving the narrow fin space. This phenomenon means that the temperature after exiting the coil is similar for all design configurations, which can be seen from the average temperature decrease ΔT in Table 1.

[0110] Figures 10-16 show simulated temperature contours for all seven system models. Unlike forced convection, which has a constant mass flow rate, natural convection has a mass flow rate that requires multiple parameters to be taken into account.

[0111] In particular, the mass flow rate introduced by the tubes of the heat transfer coil is balanced between (i) the buoyancy force derived from the temperature difference and (ii) the viscous force between the fluid and solid contact points. The buoyancy force derived from the temperature difference can be related to the density variation with temperature. It can be obtained from the momentum equation coupled with the energy equation in natural convection and Boussinesq approximation.

[0112] As shown in Table 1, when comparing the system models having a coil with a single array of "one row" tubes (i.e., System Models 1 to 5) with the system models having a coil with multiple arrays of "two rows" tubes (i.e., System Models 6 and 7), the former have a smaller average temperature decrease ΔT. This is due to the presence of bypasses at the top and bottom of the tubes of the heat transfer coil, as can be seen in Figures 10 to 14.

[0113] However, the average temperature decrease ΔT in the system models having coils with a single array of "one row" tubes (i.e., System Models 1 through 5) is not large enough to result in a significant difference in density to overcome the additional viscous forces experienced by the longer flow path in the system models having coils with multiple arrays of "two rows" tubes (i.e., Models 6 and 7).

[0114] Therefore, the system models with coils with a single array of tubes (i.e., System Models 1 through 5) result in higher mass flow rates. These reductions in heat transfer area are compensated for by the higher heat transfer coefficients that accompany the higher mass flow rates.

[0115] 17 to 22 show simulations of velocity vectors for system models 1 to 5, all of which have coils with a single array of tubes.

[0116] As shown in Figures 18-22, the first through fourth system models have less obstruction to convective fluid flow because the coils with flat tubes of rectangular cross-section and rounded edges allow for more streamlined airflow compared to tubes with circular cross-sections.

[0117] However, as shown in Figures 18-22, as the inclination angle increases, the front area of ​​the tube increases, and therefore, it receives and impedes the incoming convective fluid more. Referring to Table 1, the mass flow rate of the third system model is very close to that of the fifth system model, and the fourth system model receives a smaller mass flow rate than the fifth system model.

[0118] While the first system model can provide the best results from the simulation, the tilt angle is best implemented considering that the heat transfer coils are wet due to the formation of condensation during heat transfer. In these wet conditions, the condensation retention and drainage behavior is governed by the forces acting on the bodies, including surface tension, and the flow resistance caused by air velocity and gravity. The retention of condensation affects the thermo-hydraulic performance of the heat exchanger and the quality of the exiting convective fluid (cool air) and the comfort level within the structure.

[0119] Therefore, considering the actual situation, the second system model is the most ideal because its tubes, while having an inclined angle, have performance close to that of the first system model. This allows the second system model to improve condensation drainage because the introduced inclination forces gravity to drip condensation off the tubes. Furthermore, the tubes have a substantially rectangular cross section with rounded edges, allowing condensation to drip smoothly. Furthermore, better condensation drainage also reduces the viscous forces in the convective fluid flow, helping to remove its potential load, thereby compensating for the reduced heat transfer area.

[0120] Thus, the apparatus of the present invention, along with its associated systems and methods, provides a substantial improvement in heat exchange for passive displacement cooling, while enabling improved response times and cooling capacities to cool indoor or enclosed environments in a short period of time. Heat transfer coils having substantially rectangular cross-section tubes with rounded edges, or oval or elliptical cross-sections, and configured with an inclination angle as provided by the present invention, increase mass flow, thereby improving response times and appreciable cooling capacities.

[0121] The present invention further finds use in green buildings implementing passive displacement cooling because it solves a major obstacle to its widespread adoption. Furthermore, the reduced size of the heat transfer coil allows for reduced material costs in the construction of green buildings. Thus, passive cooling with zero air distribution energy can be provided in green buildings, saving energy by eliminating the need for mechanical fans.

[0122] This disclosure includes the subject matter of the appended claims as well as the subject matter of the foregoing description. While the present invention has been described in a preferred form with a degree of originality, it will be understood that the present disclosure of the preferred form is made by way of example only, and that many changes in the details of construction, and in the combination and arrangement of parts, may be made without departing from the scope of the invention.

Claims

1. 1. An apparatus for heat exchange, comprising: a plurality of fins; and a heat transfer coil in the form of a plurality of rectangular cross-section tubes arranged in a single array; Equipped with The fins are each vertically disposed along a longitudinal portion of the rectangular cross-section tubes and direct incoming convective fluid toward all of the rectangular cross-section tubes to effect heat exchange.

2. 10. The apparatus of claim 1, wherein each of the rectangular cross-section tubes of the heat transfer coil has a substantially rectangular cross-section with rounded edges, or has an oval or elliptical cross-section.

3. 3. The apparatus of claim 1, wherein the rectangular cross-section tube of the heat transfer coil is operably configured with a long axis of the rectangular cross-section tube at an inclination angle such that the rectangular cross-section tube is inclined relative to the direction of incoming convective fluid flowing through the heat transfer coil.

4. The apparatus of claim 3, wherein the tilt angle is substantially in the range of 0 to 60 degrees.

5. 5. Apparatus according to any one of claims 1 to 4, wherein the rectangular cross-section tube of the heat transfer coil has an aspect ratio substantially in the range of 2:1 to 5:

1.

6. 6. The apparatus according to claim 1, wherein each of the fins is formed with a plurality of holes to allow the rectangular cross-section tube of the heat transfer coil to pass through.

7. 1. A system for heat exchange, comprising: Multiple fins, a heat transfer coil in the form of a plurality of rectangular cross-section tubes arranged in a single array; and a duct housing the device; a device for heat exchange, the device having wherein the fins of the device are each disposed substantially vertically along a longitudinal portion of the rectangular cross-section tubes and direct incoming convective fluid into a duct toward all of the rectangular cross-section tubes to effect heat exchange with the outgoing convective fluid.

8. 8. The system of claim 7, wherein each of the rectangular cross-section tubes of the heat transfer coil in the apparatus has a substantially rectangular cross-section with rounded edges, or has an oval or elliptical cross-section.

9. 9. The system of claim 7 or 8, wherein the rectangular cross-section tube of the heat transfer coil in the apparatus is operatively configured with an inclination angle about a major axis of the rectangular cross-section tube so as to be inclined relative to the direction of incoming convective fluid flowing through the heat transfer coil.

10. The system of claim 9, wherein the tilt angle is substantially in the range of 0 to 60 degrees.

11. 11. The system of any one of claims 7 to 10, wherein the rectangular cross-section tube of the heat transfer coil in the apparatus has an aspect ratio substantially in the range of 2:1 to 5:

1.

12. The system according to any one of claims 7 to 11, wherein each of the fins in the device is formed with a plurality of holes to allow the rectangular cross-section tube of the heat transfer coil to pass through.

13. 13. The system of claim 7, further comprising a tray disposed below and adjacent the heat transfer coil for collecting condensation formed on the device.

14. A system according to any one of claims 7 to 13, wherein the duct comprises horizontal and vertical portions and has bends which are substantially at right angles to each other.

15. The system of claim 14 , wherein the device is positioned within the horizontal portion of the duct while adjacent to the vertical portion of the duct.

16. 16. The system of claim 14 or 15, wherein the vertical portion of the duct has a length extending from the vertical portion to a height below the horizontal portion.

17. 1. A method for heat exchange, comprising: Configuring an apparatus for heat exchange, said apparatus comprising: a plurality of fins; and a heat transfer coil in the form of a plurality of rectangular cross-section tubes arranged in a single array; a configuring step comprising: configuring a duct to house the device; Including, wherein the fins in the device are each disposed substantially vertically along a longitudinal portion of the rectangular cross-section tubes and direct incoming convective fluid into a duct toward all of the rectangular cross-section tubes to effect heat exchange with the outgoing convective fluid.

18. 18. The method of claim 17, further comprising configuring each of the rectangular cross-section tubes of the heat transfer coils in the apparatus to have a substantially rectangular cross-section with rounded edges, or to have an oval or elliptical cross-section.

19. 19. The method of claim 17 or 18, further comprising orienting the rectangular cross-section tube of the heat transfer coil in the apparatus at an oblique angle with respect to a major axis of the rectangular cross-section tube such that the rectangular cross-section tube is inclined with respect to a direction of incoming convective fluid flowing through the heat transfer coil.

20. The method according to any one of claims 17 to 19, further comprising the step of collecting condensation formed on the device by means of a tray disposed adjacent to and below the device.

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