Hybrid photovoltaic device and radiant cooling device, system, method and chiller therefor
10355154 ยท 2019-07-16
Assignee
Inventors
Cpc classification
Y02B10/20
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
F24S20/63
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Y02E10/50
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
F24S20/66
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Y02E10/40
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
H02S40/425
ELECTRICITY
Y02B10/10
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
H01L31/0521
ELECTRICITY
International classification
H01L31/052
ELECTRICITY
F24S20/63
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
A building-integrated hybrid photovoltaic and radiant cooling device integrated into a building structure, including a chiller, a cooling device for cooling fluid supplied to a radiant cooling panel, a return pipe conveying the fluid from the radiant cooling panel to cool a photovoltaic device, and at least one supply pipe transporting the fluid from the photovoltaic device to the chiller, the cooling device reducing a surface temperature of the radiant cooling panel only to the extent necessary to also avoid condensation being formed on the radiant cooling panel, i.e. to just above the dew point.
Claims
1. A building-integrated hybrid photovoltaic and radiant cooling device, comprising: a photovoltaic panel; a radiant cooling panel; a first cooling pipe in direct contact with a back surface of the photovoltaic panel; a second cooling pipe in direct contact with a back surface of the radiant cooling panel; a connecting pipe fluidly connecting the first and the second cooling pipes; a chiller fluidly connected to the first or the second cooling pipe; at least one return pipe conveying the fluid from the chiller to the first cooling pipe; and a frame configured to separate the photovoltaic panel and the radiant cooling panel and form an enclosed space defined by the frame, the photovoltaic panel and the radiant cooling panel, wherein the frame surrounds the edges of the photovoltaic panel and the radiant cooling panel, wherein a thermal insulation layer having length and width dimensions substantially the same as the frame is present in the enclosed space between the photovoltaic panel and the radiant cooling panel, and the first cooling pipe, the second cooling pipe and the connecting pipe are present in the enclosed space and wherein a gap is present between the thermal insulating layer and the second cooling pipe.
2. The building-integrated hybrid photovoltaic and radiant cooling device according to claim 1, configured to be employed with a variety of facades and roof forms, and to be mounted at a variety of inclinations.
3. The building-integrated hybrid photovoltaic and radiant cooling system according to claim 1, comprising a plurality of said building-integrated hybrid photovoltaic and radiant cooling devices adapted to be mounted in series with one another.
4. The building-integrated hybrid photovoltaic and radiant cooling device according to claim 1, further comprising an air compressor configured to be supplied with electrical power by the photovoltaic device.
5. The building-integrated hybrid photovoltaic and radiant cooling device according to claim 1, wherein the building-integrated hybrid photovoltaic and radiant cooling device is configured to operate as a window and to selectively open and close.
6. The building-integrated hybrid photovoltaic and radiant cooling device according to claim 1, wherein at least one of the first and the second cooling pipes is comprises a plurality of capillary tubes in direct contact with one of the photovoltaic panel or the a radiant cooling panel.
7. The building-integrated hybrid photovoltaic and radiant cooling device according to claim 1, wherein the radiant cooling panel and the photovoltaic device form a single integrated structure.
8. The building-integrated hybrid photovoltaic and radiant cooling device according to claim 1, further comprising a solar thermal collector.
9. The building-integrated hybrid photovoltaic and radiant cooling device according to claim 1, wherein the chiller is a thermally driven chiller.
10. A hybrid photovoltaic and radiant cooling method utilizing the building-integrated hybrid photovoltaic and radiant cooling device of claim 1, comprising: supplying a cooling fluid to a radiant cooling panel; conveying the fluid from the radiant cooling panel to cool a photovoltaic panel separated from the radian cooling panel by a gap along the flat surface of the panels; transporting the cooling fluid from the photovoltaic panel to the chiller; and reducing a surface temperature of the radiant cooling panel only to the extent necessary to also avoid condensation being formed on the radiant cooling panel.
11. The method according to claim 10, wherein the hybrid photovoltaic and radiant cooling device is configured to be employed with a variety of facades and roof forms, and to be mounted at a variety of inclinations.
12. The method according to claim 10, in which a plurality of hybrid photovoltaic and radiant cooling devices are mounted in series with one another.
13. The method according to claim 10, further comprising: supplying air compressor with electrical power by the photovoltaic device.
14. The method according to claim 10, further comprising opening and closing a window comprising the photovoltaic device and the radiating panel.
15. The method according to claim 10, wherein the hybrid photovoltaic and radiant cooling device comprises cooling pipes having capillary tubes.
16. The method according to claim 10, wherein the radiant cooling panel and the photovoltaic device form a single integrated structure.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
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DETAILED DESCRIPTION OF THE EMBODIMENTS
(21) Embodiments of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the disclosure are shown.
(22) A non-limiting embodiment of the present invention may comprise a building integrated PVT and radiant cooling device (PVTRC), as seen in
(23) In the above embodiment, radiant cooling is employed on the reverse side of the photovoltaic panels, i.e. inside the structure to be supplied with electrical power. The resulting hybrid structure is referred to as photovoltaic/thermal technology, and has at least two benefits. Not only does this reduce the temperature of the photovoltaic panels to a more efficient level, but it also cools the interior of the structure in which the panels are incorporated.
(24) Such radiant cooling systems can be constructed using tubes carrying fluid, such as water, to conduct away the excess heat, and a cooling device referred to as a chiller may be used to cool the fluid before it is supplied to the radiant cooler.
(25) Moreover, water heated by the photovoltaic devices can be employed for other purposes, such as for a potable water supply, as well as for air heating and heating building structures.
(26) The present inventors have found that these limitations of Swift et al. Can be overcome by regulating the temperature of the fluid supplied by the chiller to the level needed to prevent condensation and no lower, i.e., to just above the dew point of the atmosphere.
(27) In the device shown in
(28) Although the above embodiment is directed to cooling an electric power generation system with the aid of an electrically driven chiller, the invention is also intended to encompass the use of thermally driven chillers.
(29) Moreover, solar thermal collectors may be attached to the PVTRC to increase the temperature of the PVT return fluid for uses such as potable water heating and thermally driven cooling.
(30) In the context of the present disclosure the term building-integrated refers to an embodiment in which the PVTRC is attached or affixed to a building or configured for this purpose. In an integrated form the PVTRC may be mounted directly into a building wall, such as a replacement for an existing window, or may be separately mounted to an exterior surface of a building wall. Such mounting may include direct contact with the exterior surface of the building wall or may be offset therefrom, preferably on a steerable device to maximize the angle of incidence with solar radiation and thereby improve energy efficiency.
(31) In one embodiment a plurality of PVTRCs is connected in series or parallel on one more outer surfaces of a building, for example, a residence, a school, a factory or office building that may function as residential, commercial or industrial shelter.
(32) The PVTRC is preferably a modular unit which may be fitted as a wall piece or partition to separate exterior and interior environments of a building. In this respect the PVTRC is of construction similar to a conventional window. The surface area of the outside-facing photovoltaic panel is essentially the same as the surface area of the inside-facing radiant cooling panel. As such the PVTRC can be provided in a modular form having edges which are substantially parallel to one another and may fit easily into a partition or wall opening conventionally used for housing windows or other conventional partitioning or separating units. The PVTRC is preferably constructed such that it is in a frame which houses the PV panel and radiant cooling panel as exterior and interior-facing surfaces separated internally by a thermal insulation layer that extends over the surface area of substantially the rear portion of the photovoltaic panel.
(33) The PVTRC is preferably mounted in a frame that reflects radiant solar energy. The frame functions to hold the photovoltaic panel and the radiant cooling panel and separate them with the water circulating pipes, the thermal insulation layer and the gap. One or more supply or return points may be molded in or present on one or more edges of the frame so that the PVTRC may be directly connected or connected through one more other PVTRCs to a chiller or water storage tank. In a particularly preferred embodiment of the invention the photovoltaic panel and radiant cooling panel have a dimension that is slightly smaller than the outside dimension of the frame in which they are mounted. However the thermal insulation layer is in direct contact with each edge of the frame to thereby minimize thermal passage from interior and exterior environments of the PVTRC. In a still further embodiment the frame includes an entry or passage point for the ingress of air or a circulating gaseous material and egress of a circulating or passing gaseous material. These ingress and egress points may be used to slowly pass an inert gas or dehumidified air through one or more of the PVTRCs, individually or connected in series or connected in parallel, to further reduce the risk of condensation forming with the PVTRC module.
(34) In another embodiment of the invention the frame of the PVTRC in modular form forms a hermetic seal for the space enclosing the water circulating pipes, the thermal insulation layer and the gap between the photovoltaic panel and the radiant cooling panel.
(35) A liquid transfer pump may be included as a component of the PVTRC. The liquid transfer pump serves to circulate the water or heat transfer medium that functions to transfer heat from the photovoltaic panel to the radiant cooling panel. Preferably the pump is powered with electricity generated solely from the PV panel.
EXAMPLES
(36) The functioning of the system, device and method described herein was tested to assess the temperature increase of the PV panels and its impact on modules efficiency (, module) over one year. Tests were carried out using PolySun. Jeddah, Saudi Arabia was selected as a location for the testing. South orientation with different inclination angles were considered: 0, 22 (optimum for Jeddah), 90 and horizontal tracking. The conditions are:
(37) 1. Typical PV panel
(38) 2. PVT Panel connected to potable water storage tank (PVTHW)
(39) 3. PVTRC
(40) The results depict the impact of Tc on the module efficiency over an entire year. The calculation of the module efficiency is according to the following equation:
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(43) G: irradiance on collector area (W/A Collector)
(44) Qe,DC: direct current produced electric energy (W)
(45) The chosen PV modules FT245CS can be used for both PV and PVT systems. Table 1 outlines the main characteristics provided by the manufacturer FOTOTHERM. It is noted that the given module efficiency is 15.5%. However, this factor can only be achieved under the standard test conditions (STC) which among other conditions specifies a cell temperature of 25 C. and irradiance of 1000 W/m.sup.2.
(46) TABLE-US-00001 TABLE 1 Characteristics of Simulated PV and PVT Panels Electrical data.sup.[1] Typical power (Pn) [Wp] 245 Open circuit voltage (VOC) [V] Maximum power voltage (Vpm) [V] Short circuit current (lsc) [A] 8.74 Maximum power current (lpm) [A] 8.17 Module efficiency () [%] 15.5 Maximum system voltage [V DC] 1000 Reverse current load (lr) [A] 15 Temperature coefficient - Pn () [%/ C.] 0.43 Temperature coefficient - VPm () [%/ C.] 0.34 Temperature coefficient - lpm () [%/ C.] 0.065 Thermal data - In the case of PVT Aperture area [m.sup.2] 1.59 Thermal efficiency.sup.[2] (.sub.o) [%] 56 Nominal thermal power.sup.[3] [W] 888 Volume flow rate [l/m] 1.5-2.5 Flow losses [mmH.sub.2O] 400-900 Fluid volume [l] 0.9 Coefficient 1.sup.[2] [] 9.12 Coefficient 2.sup.[2] [] 0 Effective thermal capacity [kJ Kg.sup.1 K.sup.1] 20 IAM K0 at 50 C. Specification Cells [] 60 poly-Si Thickness [mm] 156 Electrical connectors [] MC4 Hydraulic connector [*] female Dimensions [mm] 1638 982 41 Weight [kg] 27 .sup.[1]STC condition: irradiance = 1000 W/m2, cell temperature = 25 C. .sup.[2]Based on aperture area .sup.[3]PV OFF conditions referred to (Tm Ta) = 0
Typical PV Panel:
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(48) The maximum achievable e,DC among different inclination angles was 13% in March using a vertical module.
(49) PVT Connected to Potable Water Storage Tank:
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(52) A considerable decrease in Tc, max can be seen in
(53) PVTRC:
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(55) As in other embodiments described herein,
(56) In some embodiments the PVTRC is limited to cooling energy generation with the aid of electrical driven chiller further. Other embodiments permit the utilization of thermally driven chillers. Still further embodiments include on or more solar thermal collectors attached to the PVTRC to increase the temperature of the PVT return water (PVTWR) to reach a desired level for a specific use like potable water heating or thermally driven cooling.
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(64) Steady state CFD simulations using Ansys Fluent were conducted to demonstrate the temperature distribution on the panel by changing Ta and G. Table 2 outlines the material properties of the simulated PVTRC. The considered mass flow rate of water is 0.025 kg/s.
(65) TABLE-US-00002 TABLE 2 Material properties of the PVTRC. PV-Absorber Density [kg/m.sup.3] 2330 Cp (Specific heat) [J/kg .Math. K] 700 Thermal conductivity [W/m .Math. K] 131 Copper Density [kg/m.sup.3] 8978 Cp (Specific heat) [J/kg .Math. K] 381 Thermal conductivity [W/m .Math. K] 387.6 Water Density [kg/m.sup.3] 998.2 Cp (Specific heat) [J/kg .Math. K] 4182 Thermal conductivity [W/m .Math. K] 0.6 Viscocity [kg/m .Math. s] 0.001003 Insulation Density [kg/m.sup.3] 200 Cp (Specific heat) [J/kg .Math. K] 1000 Thermal conductivity [W/m .Math. K] 0.035 Aluminum Density [kg/m.sup.3] 2719 Cp (Specific heat) [J/kg .Math. K] 871 Thermal conductivity [W/m .Math. K] 202.04 Air Density [kg/m.sup.3] 1.225 Cp (Specific heat) [J/kg .Math. K] 1006.43 Thermal conductivity [W/m .Math. K] 0.0242 Viscocity [kg/m .Math. s] 1.79E05
(66) Climate conditions of three different scenarios were considered: STC, winter and summer. The used input data for each scenario are shown in Table 3. The selected data refer to the climate condition of the standpoint: Jeddah, Saudi Arabia. However, the PVTRC device can be used in other locations.
(67) TABLE-US-00003 TABLE 3 Climate scenarios tested. STC Ta [ C.] 25 G [W/m.sup.2] 1000 Winter Ta [ C.] 32 G [W/m.sup.2] 261 Summer Ta, max [ C.] 41 Gmax [W/m.sup.2] 67
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(69) Under the STC condition, despite the low Ta of 25 there is a remarkable increase in temperature distribution. The main cause is the increased irradiance of 1000 W/m2. However, significant decrease in temperature is noted due to the circulating water at the back supplied at a temperature of 25 C. Clearly, the surface temperature of a large portion of the panel is around 31 C. The image in the middle represents the winter scenario where the altitude of the sun is low. The south faade is usually affected with high irradiance that reaches 261 W/m2. This value as well as the maximum ambient temperature in winter of Ta=32 C. was used in the simulation. In summer, 67 W/m2 and 41 C. were considered in the input parameter. In both scenarios, considerable reduction in the module temperature has achieved and surface temperature between 25-30 C. is demonstrated.
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(71) In embodiments the PVTRC of the present disclosure provides: Higher PV efficiency through lower water supply temperature which is supplied through the coupling of PVT with a radiant cooling panel whereby a connection is made via an extra pipe that links the return water to the supply water of the PVT. Cooler PVT surface temperature. Practical application for building faade/wall integrated devices as the surface temperature is low. Space saving by combining radiant cooling panel with PVT in one device in the same portion of the external wall. As high cooling loads coincide with high faade irradiance cooling energy can be directly generated via electric compressor connected to the PVT. No energy storage is required. Use with different inclinations, facades and roof forms. Connectable in series and with varied sizes. Operable and functional as a window to allow fresh air intake in times of pleasant temperature. Higher performance achieved using capillary tubes on both panels instead of copper pipes.