Exergy analysis of an experimental heat transformer for water purification

Rivera, W.; Huicochea, A.; Martínez, H.; Siqueiros, J.; Juárez, D.; Cadenas, Erasmo

doi:10.1016/j.energy.2010.10.036

“…As an instance, Fig. 3 shows the same system operating in two different conditions, respectively test1 (filled markers) and test2 (empty markers) from [14], making evidence of the fact that an increase of the temperature difference at either the absorber or the generator/evaporator increase the efficiency. However, the values of the temperature parameters are required to positive and limited to those giving positive values of G, standing for the total irreveribilities.…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, if the COP value is fixed, the main dimensionless parameters for system design can be related as follows. Table 2 from the data used as a reference [14]) as analytically expressed in Eq. (20) and Eq.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Thermodynamic Analysis of Irreversible Heat-transformers

Giannetti¹,

Arnas²,

Rocchetti³

et al. 2015

MST

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Absorption heat transformers extend the possibilities for efficient and environment-friendly energy conversion processes. Based on a general thermodynamic model of three-thermal cycles with finite thermal capacity of the heat sources, this paper is intent upon analyzing and optimizing the performance of absorption heat transformers, by including the influence of irreversibility in the analytical expression of the system efficiency. Dimensionless parameters for an overall optimization are defined and a first screening is performed to clarify their influence. Dependence on the main factors is highlighted to suggest how to change them in order to enhance the whole system performance. Under this point of view, the analysis evaluates coefficient of performance (COP) improvements and can be used to perform existing plant diagnostics, besides predicting the system performance. The use of this criterion is exemplified for specific heat transformers data from literature. This approach identifies the limitations imposed to the physical processes by accounting for the inevitable dissipation due to their constrained duration and intensity, and constitutes a general thermodynamic criterion for the optimization of three-thermal irreversible systems. AbstrakAnalisis Termodinamika Ireversibel Heat-transformator. Penyerapan panas transformator memperluas kemungkinan adanya proses konversi energi yang efisien dan ramah lingkungan. Berdasarkan model termodinamika umum siklus three-thermal dengan kapasitas termal yang terbatas dari sumber panas, tulisan ini bertujuan untuk menganalisis dan mengoptimalkan kinerja penyerapan panas transformator, dengan memasukkan pengaruh ireversibilitas dalam ekspresi sistem analitis efisiensi. Parameter berdimensi untuk optimasi secara menyeluruh dan yang pertama dilakukan adalah penyaringan untuk memperjelas pengaruh masing-masing. Ketergantungan pada faktor utama menyoroti dan menunjukkan bagaimana mengubah mereka untuk meningkatkan kinerja sistem secara keseluruhan. Melalui sudut pandang ini, analisis evaluasi perbaikan COP dapat digunakan untuk melakukan diagnosis tanaman yang ada, selain memprediksi kinerja sistem secara keseluruhan. Pendekatan ini mengidentifikasi keterbatasan dalam proses fisik, yang berkontribusi untuk pembuangan tidak terelakkan terkendala lamanya penyinaran dan intensitas, merupakan sebuah kriteria termodinamika umum untuk optimalisasi sistem three-thermal ireversibel.

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“…These graphs make evidence of the occurrence of a constantly increasing COP with reference to t H and t M , but decreasing with t L . Dashed lines are obtained for the literature value of the secondary variable considered in each graph and the markers represent the operative condition of the real system from [14]. By comparing the actual efficiency with the performance maps obtained, it is possible to perform system diagnostic and show how to improve the overall system efficiency.…”

Section: Resultsmentioning

confidence: 99%

“…Considering data from [14], increasing the temperature difference at the high and intermediate temperature heat exchangers, for the same low temperature conditions, or, ceteris paribus, decreasing the temperature difference at the condenser, will bring the system to higher first law efficiency. As an instance, Fig.…”

Section: Resultsmentioning

confidence: 99%

Thermodynamic Analysis of Irreversible Heat-transformers

Giannetti

¹

,

Arnas

²

,

Rocchetti

³

et al. 2015

MST

3

0

View full text Add to dashboard Cite

Absorption heat transformers extend the possibilities for efficient and environment-friendly energy conversion processes. Based on a general thermodynamic model of three-thermal cycles with finite thermal capacity of the heat sources, this paper is intent upon analyzing and optimizing the performance of absorption heat transformers, by including the influence of irreversibility in the analytical expression of the system efficiency. Dimensionless parameters for an overall optimization are defined and a first screening is performed to clarify their influence. Dependence on the main factors is highlighted to suggest how to change them in order to enhance the whole system performance. Under this point of view, the analysis evaluates coefficient of performance (COP) improvements and can be used to perform existing plant diagnostics, besides predicting the system performance. The use of this criterion is exemplified for specific heat transformers data from literature. This approach identifies the limitations imposed to the physical processes by accounting for the inevitable dissipation due to their constrained duration and intensity, and constitutes a general thermodynamic criterion for the optimization of three-thermal irreversible systems. AbstrakAnalisis Termodinamika Ireversibel Heat-transformator. Penyerapan panas transformator memperluas kemungkinan adanya proses konversi energi yang efisien dan ramah lingkungan. Berdasarkan model termodinamika umum siklus three-thermal dengan kapasitas termal yang terbatas dari sumber panas, tulisan ini bertujuan untuk menganalisis dan mengoptimalkan kinerja penyerapan panas transformator, dengan memasukkan pengaruh ireversibilitas dalam ekspresi sistem analitis efisiensi. Parameter berdimensi untuk optimasi secara menyeluruh dan yang pertama dilakukan adalah penyaringan untuk memperjelas pengaruh masing-masing. Ketergantungan pada faktor utama menyoroti dan menunjukkan bagaimana mengubah mereka untuk meningkatkan kinerja sistem secara keseluruhan. Melalui sudut pandang ini, analisis evaluasi perbaikan COP dapat digunakan untuk melakukan diagnosis tanaman yang ada, selain memprediksi kinerja sistem secara keseluruhan. Pendekatan ini mengidentifikasi keterbatasan dalam proses fisik, yang berkontribusi untuk pembuangan tidak terelakkan terkendala lamanya penyinaran dan intensitas, merupakan sebuah kriteria termodinamika umum untuk optimalisasi sistem three-thermal ireversibel.

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Upgrading Waste Heat from 90 to 110 °C: The Potential of Adsorption Heat Transformation

Engelpracht

¹

,

Gibelhaus

²

,

Seiler

³

et al. 2020

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Globally, heat demand accounts for 71% of industrial energy consumption. [1] For example, the industry in the US requires 3416 PJ heat between 40 and 260 C, with 1755 PJ already in the temperature range between 120 and 160 C, and the industry in the European Union requires 626 PJ heat for temperatures below 150 C, with 116 PJ in the temperature range between 100 and 150 C. [2] Examples of such industrial processes and their process temperatures were summarized by Arpagaus et al. or Brückner et al. (Table 1). [2,3] Simultaneously, the global industry releases 31902 PJ of waste heat, with 42% occurring below 100 C as low-grade heat. [4] Transforming this low-grade waste heat from temperatures below to above 100 C could enhance industrial energy efficiency. Thereby, heat transformation has the potential to reduce both primary energy consumption and greenhouse gas emissions. [5] The low-grade waste heat can be transformed into useful heat with higher temperatures by mechanically driven vapor compression heat pumps or thermally driven heat transformers. However, classical heat pumps currently available are restricted to a maximum gross temperature lift of 50 K and a maximum condensing temperature of 130 C. [2,6] Vapor compression heat pumps for higher temperatures suffer from the lack of suitable working fluids. [2,6] Designs are often challenging for both the cycles (e.g., multi-stage cycles) and components (e.g., multi-stage compressors) due to high discharge pressures and temperatures. [2,6-8] To overcome these limitations, many researchers screen working fluids or improve the thermodynamic cycle design. For example, Mikielewicz and Wajs screened working fluids with low global warming potential for upgrading heat from 50 to 130 C. [6] Ethanol was identified as a promising working fluid in a singlestage cycle design, whereas multi-stage cycles generally seemed

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Exergy analysis of an experimental heat transformer for water purification

Cited by 65 publications

References 19 publications

Thermodynamic Analysis of Irreversible Heat-transformers

Thermodynamic Analysis of Irreversible Heat-transformers

Thermodynamic Analysis of Irreversible Heat-transformers

Upgrading Waste Heat from 90 to 110 °C: The Potential of Adsorption Heat Transformation

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