Diagnostic method of solar thermal system based on the short time on-line measurements

Obstawski, P.; Bakoń, T.; Czekalski, D.

doi:10.1016/j.applthermaleng.2018.11.048

Cited by 5 publications

(7 citation statements)

References 33 publications

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“…The basis for the methodology and the application of the parametric identification method used in solar installation diagnostics was developed by Obstawski [59] ( Table 1). The developed method has been modified twice [60,61]. The author used the parametric identification method (PI) to determine the dynamic parameters of a solar installation under operating conditions.…”

Section: An Overview Of Test Methods For Flat-plate Solar Collectorsmentioning

confidence: 99%

“…In order to perform a comparative analysis, the static and dynamic properties of a solar collector will be determined using three methods: the steady state method according to the quality standard ISO 9806 under outdoor conditions [20], the ETN method developed by Chochowski [44] and the PI method developed by Obstawski [61]. The produced results shall be compared to the static and dynamic properties determined by the producer according to the quality standard ISO 9806 under indoor conditions and listed in the technical documentation of the collector.…”

Section: Methodsmentioning

confidence: 99%

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Comparison of Solar Collector Testing Methods—Theory and Practice

2020

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One of the most important problems of operating solar heating systems involves variable efficiency depending on operating conditions. This problem is more pronounced in hybrid energy systems, where a solar installation cooperates with other segments based on conventional carriers of energy or renewable sources of energy. The operating cost of each segment of a hybrid system depends mainly on the resulting efficiency of solar installation. For over 40 years, the procedures of testing solar collectors have been undergoing development, testing, comparison and verification in order to create a procedure that would allow determining the thermal behavior of a solar collector without performing expensive and complicated experimental tests, usually based on the steady state condition. The proper determination of the static and dynamic properties of a solar collector is of key significance, as they constitute a basis for the design of a solar heating installation, as well as a control system. It is therefore important to conduct simulating and operating tests enabling the performance of a comparative analysis intended to indicate the degree to which the static and dynamic properties of a solar collector depend on the method used for their determination. The paper compares the static and dynamic properties of a flat solar collector determined by means of various methods. Based on the produced results, it has been concluded that the static and dynamic properties of a collector determined using various methods may differ from each other even by 50%. This means that it is possible to increase the efficiency of a solar heating installation via the use of an adaptive control algorithm, enabling real-time calculation of the values of characteristic parameters of solar installation, e.g., the time constant under operating conditions.

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Section: An Overview Of Test Methods For Flat-plate Solar Collectorsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Comparison of Solar Collector Testing Methods—Theory and Practice

2020

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“…The general form of the model of state variables is presented by two matrix equations: the equation of state (1) and the equation of output (2). To determine the state transition matrix, the values of all state variables must have a value of '0' except for one state variable, which must have a value of '1'.…”

Section: Pi and Etn Based Diagnostic Methodsmentioning

confidence: 99%

“…In case of thermal objects such as flat-plate solar collector, they are determined on the basis of step response determined during normative tests carried out in accordance with ISO 9806:2017 [1]. The standard only specifies the methodology for determining the equivalent time constant, omitting the gain factor and the delay time [2]. The dynamic properties of a collector may be determined using numerous methods based on the energy balance of the collector and enabling the analysis of its thermal conditions [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, it is important to determine the dynamic properties of a solar heating installation under operating conditions. Such possibilities are provided by the diagnostic method of the solar heating installations based on the comparison of two models: a digital model of differential equations developed on the basis of operating data using the method of parametric identification (PI) and an analogue model derived from the energy balance [2]. The method allows to determine the values of collector parameters under operating conditions treated as characteristic values, among others: heat loss coefficient UL, heat removal factor FR, heat capacity (mc)e. A more detailed analysis of the heat transfer process in a flat-plate liquid collector is provided by the diagnostic method of solar heating installations based on a comparison of a digital model developed based of operating data using the method of parametric identification and an analogue model in the form of Equivalent Thermal Network (ETN).…”

Section: Introductionmentioning

confidence: 99%

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Analysis of thermal states of a flat-solar collector using state variables

2020

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This paper analyses the thermal states of the flat solar collector using the state variable method. The knowledge of the transient states describing the state of the solar heating installation under operating conditions enables the analysis of the heat exchange process and the development of control strategies. The analysis of variable states under operating conditions requires the development of a mathematical model describing the dynamic properties of the whole solar heating installation and the definition of the variables describing the state of the system from the energy balance perspective. The paper presents a method enabling the analysis of variables in the condition of a solar heating installation and a single solar collector based on the comparison of two models: an analogue model developed by the Equivalent Thermal Network method and a digital model, developed on the basis of performance data by the Parametric Identification method.  Corresponding author: pawel_obstawski@sggw.pl

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