Available online at www.sciencedirect.com
ScienceDirect Energy Procedia 00 (2016) 000–000 www.elsevier.com/locate/procedia
3rd International Conference on Energy and Environment Research, ICEER 2016, 7-11 September 2016, Barcelona, Spain
Optimizing and controlling the productivity of a flat plate collector by using an electronic system Kamal Anoune1,2*, Mohsine Bouya1, Abdellatif Ben Abdellah2 , Abdelali Astito2 1
Laboratory of Renewable Energies and Advanced Materials, International University of Rabat (UIR), Sala Al Jadida 11100, Morocco. 2
Laboratory of Informatics, Systems &Telecommunications FST- Abdelmalek Essaadi University (UAE) Tangier, Morocco.
Abstract The Flat Plate Collector (FPC) is a thermal solar collector used in housing or residential applications. It allows the conversion of solar radiation to thermal energy (e.g. hot water). In this paper we propose a new approach that improves the hot water production through the combination between a simple and improved architecture model (e.g. electronic control & thermal process) of the FPC. While the optimization of the thermal energy efficiency is guaranteed by using an electronic architecture that controls the mono-axial tracker and provides the on request of the hot water by using an electric resistance. Finally, we have conducted several experimental tests aiming the comparison between the stationary and improved FPC, while we use several curves and graphics in order to present the gain obtained in the thermal energy taking into consideration the global solar radiation, thermal energy production, electrical power consumption and residential consumer behavior of hot water. Keywords: Energy efficiency, Thermal collector, Flat-plate collector, Incidence angle modifier, Renewable energy, Electronic systems.
1. Introduction The solar tracker are used to increase the solar radiation exposure in an optimum manner, it optimizes the performance of a remarkable way relative to a fixed installation. So we opted for the use of a solar tracking system with tree optimal angles in order to minimize electrical consumption of tracker, several studies are made to improve the energy efficiency of each FPC or PV systems, especially photovoltaic system who know a great worldwide reputation. [1] A study to optimize the energy productivity of the flat-plate collector, studying the impact of the incidence angle modifier on the energy performance. However, a new design and the architecture [2,3] of an intelligent tracker that gives an electronic architecture, it remotely using the two-axis trackers in order to improve energy production for PV. A comparison of three different collectors for process heating applications [4] shows a result of measuring the effectiveness of the collector and of the incidence angle modifier next, an evaluation of a tracking flat plate solar collector in Brazil [5] shows the useful energy gain and efficiency of a flat plate solar collector were evaluated for a period of one year. finally a plurality of sun tracking systems was compared to fixed devices, [7] discuss an approach to improve the productivity of a FPC by using a mono-axial tracker while a prediction study have been done to compare a fixed model in south orientation with a model with a mono-axial tracker. Otherwise, a series of experimental tests have been held for the two systems aiming their comparison of their productivity over time along the day. In this article, we use a mathematical model to define efficiency and calculate the energy absorbed by the solar collector FPC, we also call equations of efficiency to show the impact on performance causing by IAM (incidence angle change) on thermal productivity of the collector. We propose after a design of an electronic control system dedicated to the piloting the tracker and an operating algorithm of the mono-axial tracker with three positions. We will provide a test bench for our thermal system including a dynamic and a static FPC, taking into consideration the same technical configuration of the both solar collector to achieve the solar performance testes, * Corresponding author. Tel.: +212 663 134 673; fax: +212 530 103 000. E-mail address:
[email protected] 1876-6102 ©2016 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the organizing committee of ICEER 2016.
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Kamal Anoune, Mohsine Bouya, Abdellatif Ben Abdellah and Abdelali Astito / Energy Procedia 00 (2016) 000–000
and the hot water productivity. While we carrying out its tests for our new improved thermal systems that include the FPC thermal collector equipped with an intelligent electronic system specially designed for controlling a monoaxial tracker with three positions, then a circulation pump the heat transfer fluid, after that a storage tank, finally setting a thermal heating resistor. In the end, we discuss the results of experimental tests of the thermal systems taking into consideration the graphs of solar radiation light energy, the hot water productivity and the influence of the consumption behavior of hot water on the electrical consumption, these tests are performed separately for stationary and improved FPC. Tm Ta a1 a2 F′ Kθ K θL K θT (𝝉𝜶)𝒆 (𝝉𝜶)𝒆𝒏
Nomenclature Qa m 𝐶𝑝 𝑇0 𝑇𝑖 A η0 G η
Heat gain of fluids (W). Mass flow rate, kg/s. Heat capacity of water (J/ (kg K). Outlet fluid temperature (°C). Inlet fluid temperature (°C). Surface area of solar collector (m²). Optical efficiency. Global solar radiation (W/m2). Collector operating efficiency.
Average temperature in the collector (°C). Ambient temperature (°C). First order heat loss coefficient Second order heat loss coefficient Collector efficiency factor Incidence angle modifier Longitudinal incident angle modifier Transversal incident angle modifier Effective transmittance – absorbance product. Normal incidence
2. Impact on performance of a solar thermal collector as a result of the IAM (Incident Angle Modifier): The heat gain of fluids is given by the expression: Q a = m𝐶𝑝 (𝑇0 − 𝑇𝑖 ) (1) (2) Q a = A. η0 . G The optical efficiency of the collector FPC is: η0 = τs . αs (3) The efficiency of a solar heating collector can be characterized by three independents coefficients of temperature, and can be calculated at any operating point using an equation in the following form: (Tm − Ta ) (Tm − Ta )2 (4) η = η0 − a1 .
G
− a2 .
G
Global solar radiation cannot be perpendicular to the planar surface of the collector only for a few minute, there is often an angle of incidence which is denoted θ, the direction of incidence is not only described by this single angle, but from two different transverse and longitudinal, described by the symbol 𝐊 𝛉 is showed in the efficiency formula. If the incidence angle modifier is introduced in the equation, the effective transmittance – absorbance product (𝛕𝛂)𝐞 can be replaced by the value at normal incidence(𝛕𝛂)𝐞𝐧 . η = F ′ . K θ . (τα)en − a1 . (τα)e = K θ . (τα)en
(Tm −Ta ) G
− a2 .
(Tm −Ta )2 G
Witch the multiplication ofK θL and K θT Equal: K θ = K θL . K θT
Fig.1. the incident angle modifier IAM, on the exposed surface of the collector
(5) (6)
(7)
Kamal Anoune, Mohsine Bouya, Abdellatif Ben Abdellah and Abdelali Astito / Energy Procedia 00 (2016) 000–000
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The plane surface of the thermal collector receives solar radiation at the order of 1000W/m² in sunny conditions (clear sky), but the incidence angle of solar radiation projected on the thermal collector, influences its thermal efficiency with a remarkable manner "fig.1". Angle of incidence of sunlight on the collector surface
Table 1: Impact of angle of incidence The absorptive power By 1 m² of FPC
% Of solar radiation on FPC
00° 30° 45° 75° 90°
1000W/m² 860W/m² 700W/m² 258W/m² 0W/m²
100,00% 86,00% 70,00% 25,80% 0,00%
This table shows the effect of IAM (incidence angle modifier) on the received power of the light energy which provided in contact with the solar collector. In deed it is based on the data provided by an average curve of FPC solar transmittance, until now we can deduct from the table "Fig.1" that the thermal collector provides an optimal performance characteristics between 70% and 100% if the IAM remains lower than 45°, otherwise we notice that the FPC energy performance drops exponentially. In the final analysis, we opted to maintain the interval of IAM between 0° and 45°, and we equip FPC with a single-axis tracker in order to maintain the optimum performance of the collector. 3. Description of the test bench of the thermal collector system In the first place, the heat system illustrated in "Fig.2" is designed by an FPC that allows the collection and conversion of solar radiation into hot water through the absorbers. Next, this FPC is equipped with a mechanical system making a horizontal rotation, it is controlled by an electronic system that is designed and made in this respect, finally a buffer storage tank designed to meet the needs of six people sanitary hot water (380 liter). This tank contains a heat exchanger that carries out the heat transfer from the heat transfer fluid coming from the FPC and the existing water in the tank. The heat exchanger allow the water heating and consequently its temporary storage, this tank contains an electrical heater (electrical resistance) in thermal supply event of an overload consumer demand of the hot water during the night or early in the day. We added a small circulation pump the heat transfer fluid between the FPC and the heat exchanger, and also sensor/temperature transmitters and a flow meter allowing the collection in real-time information about our system.
TT3 FT1
Cold Water (Input)
TT 1
TT2
Hot Water (Output)
TT4
Fig.2. functional scheme of the system
An electronic system is designed to appeal to various requirements (control and command) of our improved thermal system, otherwise it ensure the production improvement of hot water during all seasons of the year. Additionally the electronic system manages the mono-axial tracker that provides 3 daily positions because FPC tolerates an angle of incidence 45 °.
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Kamal Anoune, Mohsine Bouya, Abdellatif Ben Abdellah and Abdelali Astito / Energy Procedia 00 (2016) 000–000
4. Electronic system architecture The electronic system manages the improved functioning of the FPC, indeed, it ensures in priority the orientation of the FPC thermal collector with 3 positions in order to maximize exposure to sunlight and then increase the productivity of hot water, then regulating the fluid circulation pump, finally, making a regulation of the heating resistor in the event of the request. The architecture of the electronic system is around a powerful 18F4550 microcontroller that provides logical processing and arrhythmic necessary to respond to the multi-function to insured, she runs the preconfigured program in its ROM, firstly it ensures the collection of information needed through the various sensors (temperature, flow rate, encoder, etc.…). It controls the rotation in three positions using single-axis tracker, then she realizes the control of the circulation pump, and the regulation of the electrical resistance heating, and finally the system has an alphanumeric display for visualizing the system status in real time (azimuth position, RTC, electric heating, fluid movement speed, etc.…). Flow Meter: allows the flow control of the hot water consumption
Slewing Drive Motor (Tracker): Control & Protection
Control and power system PIC Microcontroller: information processing. Temperature sensor: measures the ambient temperature of the card. Position control algorithm (tree position orientation). Digital display: management services display. Power control: (H bridge) Slewing Drive Motor. Power control: Circulation Pump. Power control: electrical resistance heating RTC: Real Time Clock
Circulation Pump of heat transfer fluid: Control & Protection
Temperature Sensor: allows temperature measurement in real time at the output of each subsystem. Encoder: an electronic sensor allowing to determinate the collector position
Electrical resistance heating: allows heating of the tank in case of on request.
Fig. 3. Diagram of the electronic architecture of the thermal system
The "Fig. 3" diagram shows the hardware architecture of the electronic system that provides control and command, this architecture provides several features described in the operation algorithm in the next chapter, they composed by several input / output modules: Temperature Sensor: four temperature sensors/transmitters that allows temperature measurement in real time in the output of each subsystem and shipments of such information to the electronic system. Flow Meter: allows the flow measurement of the hot water consumption. Encoder: an electronic sensor allowing to determinate the collector position. Slewing Drive Motor (Tracker): a mechanical system, which supports the vertical metal rod containing both PFC and allows horizontal rotation through a DC motor. Pump circulation of heat transfer fluid: it allows the movement of the water between the FPC thermal collector and exchanger located at the tank. Electrical resistance heating: allows the water heating located at the tank in case of on request. 5. The operating algorithm of the electronic system: The diagram "Fig.4" illustrates the behavior of the electronic system according various input-output. In other words, it can generate the signals command of (circulation pump, heat resistance, etc.). In addition controlling the slewing drive motor, and compensating the energy difference manifested by strong demand using an electric heater. Moreover, the electronic system interprets the signals control (temperature T1, T2, T in, T out, and flow, etc.). In order to maintain a continuous production of hot water at 65°C, for 24h/24 and 7d/7 during the year. The electronic system first will control the horizontal rotation of the FPC on three positions during the day, in order to maximize exposure to sunlight and have maximum production, Finally an enslavement command in the circulation pump of the heat transfer fluid as a function of (T1 and T2), and actuate the electrical heating resistance in the event of need.
Kamal Anoune, Mohsine Bouya, Abdellatif Ben Abdellah and Abdelali Astito / Energy Procedia 00 (2016) 000–000
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Starting System Settings Initializing T1, T2, Tin, Tout Values Flew meter value Encoder angle value RTC Setting
Data Acquisitions Treatment
T1, T2, Tin, Tout Values Flew meter value Encoder angle value RTC Setting
Setting Display
NO
YES
Generate Angle
RTC=06h30
YES
NO
FPC move to 120° Circulation Pump ON
T out < 35°
YES
NO
RTC=10h30
Resistance heating ON
Heating water
YES
NO
FPC move to 180° Circulation Pump ON
Generate Angle
T out >65°
YES
NO
STOP heating water
RTC>15h00 RTC
