Thermal modelling of a flat plate solar collector with latent heat storage validated with experimental data in outdoor conditions

Carmona, Mauricio; Palacio, Mario

doi:10.1016/j.solener.2018.11.056

Cited by 64 publications

(23 citation statements)

References 39 publications

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“…Additionally, they included the average of the surface area of the tube containing the PCM and the reference (A c and A c ), Equations (2) and 3to calculate c p,l , c p,s are transformed into:…”

Section: Determination Of Thermal Properties Using the T-history Methodsmentioning

confidence: 99%

“…The interest in phase change materials (PCM) grows continuously due to its wide application in sectors as the storage of solar thermal energy, industrial heat recovery, construction, agricultural greenhouses, aerospace, health, refrigeration, among others [1][2][3]. An adequate characterization is a mandatory requirement for numerical modeling of processes involving PCM, equipment design, and the development of this technology and its applications, since thermal characterization provides information about the amount of energy that a material can store.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of Thermophysical Properties of Phase Change Materials Using Unconventional Experimental Technologies

et al. 2020

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The growing interest in developing applications for the storage of thermal energy (TES) is highly linked to the knowledge of the properties of the materials that will be used for that purpose. Likewise, the validity of representing processes through numerical simulations will depend on the accuracy of the thermal properties of the materials. The most relevant properties in the characterization of phase change materials (PCM) are the phase change enthalpy, thermal conductivity, heat capacity and density. Differential scanning calorimetry (DSC) is the most widely used technique for determining thermophysical properties. However, several unconventional methods have been proposed in the literature, mainly due to overcome the limitations of DSC, namely, the small sample required which is unsuitable for studying inhomogeneous materials. This paper presents the characterization of two commercial paraffins commonly used in TES applications, using methods such as T-history and T-melting, which were selected due to their simplicity, high reproducibility, and low cost of implementation. In order to evaluate the reliability of the methods, values calculated with the proposed alternative methods are compared with the results obtained by DSC measurements and with the manufacturer’s technical datasheet. Results obtained show that these non-conventional techniques can be used for the accurate estimation of selected thermal properties. A detailed discussion of the advantage and disadvantage of each method is given.

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Section: Determination Of Thermal Properties Using the T-history Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterization of Thermophysical Properties of Phase Change Materials Using Unconventional Experimental Technologies

et al. 2020

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“…The choice to adopt a hybrid model is due to different factors. The one-dimensional model that describes all the sections of the collector going from its external surface to the storage cavity simplifies the computational cost without leading to serious discrepancies with respect to reality, as already demonstrated in numerous studies (Azzolin et al, 2018;Carmona and Palacio, 2019). The same approach cannot be adopted for the PCM cavity since the geometry of the honeycomb cells induces a temperature gradient both in the axial direction (x in Figure 5) and in the radial direction (y in Figure 5), even though the gradient is lower in the radial direction.…”

Section: Modeling Of the Icsmentioning

confidence: 98%

Modelling and performance analysis of a new concept of integral collector storage (ICS) with phase change material

et al. 2019

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Solar Domestic Hot Water (SDHW) systems represent a constantly evolving technology in today's applications. With the new directives promoted by the European Union the renewable energy share produced in buildings will tend to increase further. Research on how to increase the efficiency of the thermal production from renewable energy are therefore of the foremost importance. This study aims to investigate the energy performance of an integral collector storage (ICS) prototype for DHW production. This ICS represents a new concept technology, integrating inside the same device a flat plate absorber and a storage section with phase change material (PCM) connected by heat pipes filled with methanol. An objective of this study was to investigate a possible alternative to conventional solar systems, with the aim of reducing investment costs and improving system reliability without compromising energy performance. The energy assessment was carried out using a numerical model in the Engineering Equation Solver (EES) environment, following an electrical analogy scheme. After a validation process by means of experimental data, a yearly simulation was launched in order to estimate the productivity and the solar fraction of the prototype. The results obtained allowed a global energy evaluation and a comparison with similar systems and to identify the pros and cons of this new technology.

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“…The base equations for each component of the solar ORC system are summarized in Table 2, with the heat transfer coefficients, regulating the heat exchange, as in [38][39][40].…”

Section: Combined Heat and Power System Modelingmentioning

confidence: 99%

Multi-Variable Control and Optimization Strategy for Domestic Solar-ORC Combined Heat and Power Generation System

et al. 2020

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The feasibility of a solar-ORC system for domestic combined heat and power generation (CHP) is deeply affected by both the time-varying ambient conditions (e.g. solar irradiance, temperature, wind speed) and the thermal and electrical load profiles variability of the final application. The definition of a proper control strategy is proven to be a major design-challenge for successful operation of solar-ORC systems, with the main goal of assuring that the thermal power demand for space heating and Domestic Hot Water (DHW) production and the electricity needs are simultaneously satisfied. The rising demand for energy-autonomous systems also calls for the inclusion of a storage system within the base-layout, that could assure the electricity demand is properly matched after sunset or in very-low irradiance conditions, such as cloudy days. A comprehensive model accounts for the dynamic of the plant-integrated unit, featuring an ORC-based plant that bottoms a flat plate solar thermal collector: a parametric study is presented, and an off-design analysis is performed to properly assess the energy performance of the system. The heat availability to the ORC heat exchanger is evaluated, based on solar availability, thermal losses in the pipes and plant requirements, in terms of operating temperature and pressures and organic fluid mass flowrate. R245fa is selected as working fluid in the ORC-section. Sliding vanes machines expander and pump – are considered as rotary equipment. Flat plate heat exchangers complete the base layout, the analysis accounts for. Due to the need for DHW production, a storage unit for hot water is present, upstream the recovery branch: dependently on the ability the fluid at the collector outlet has to meet the ORC requirements for proper operation (about 110°C), the ORC evaporator is fed and the recovery section enabled. Both continuous and unsteady operation underwent an in-depth analysis, as well as the benefits associated with different discharge times for the storage unit. A dedicated control strategy is defined, dependently on whether the electrical output or the thermal one need to be maximized, and accounts for either a flash or a progressive tank discharge. A virtual platform allowed the setting-up of a pilot plant, for direct performance assessment, in presence of different amounts of tank discharges per day and different lower temperatures at the storage tank.

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Thermal modelling of a flat plate solar collector with latent heat storage validated with experimental data in outdoor conditions

Cited by 64 publications

References 39 publications

Characterization of Thermophysical Properties of Phase Change Materials Using Unconventional Experimental Technologies

Characterization of Thermophysical Properties of Phase Change Materials Using Unconventional Experimental Technologies

Modelling and performance analysis of a new concept of integral collector storage (ICS) with phase change material

Multi-Variable Control and Optimization Strategy for Domestic Solar-ORC Combined Heat and Power Generation System

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