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9 results on '"solar storage tank"'

1. Analysis of the Stratified Storage Model from the New prEN 15 316-5 : 2023

Author

Sinčić, Jakša, Horvat, Ivan, Dović, Damir, Filipović, Petar, Dović, Damir, Soldo, Vladimir, and Mudrinić, Saša

Subjects
solar storage tank, stratified storage model, solar system, CFD simulation, solar collector thermal efficiency
Abstract

In 2017, CEN (European Committee for Standardization) introduced a 2nd edition of standards for the assessment of buildings technical system energy performance (EN 15316 series of standards) supporting the Energy Performance of Buildings Directive. The main novelty is the introduction of an hourly time step calculation methods and of the new standard which takes into account dynamic temperature variations within the storage tank (EN 15316-5:2017). This standard contained many errors in the provided energy balance equations and ambiguities related to calculation procedure. Therefore, the revision of this standard has been made (prEN 15316-5:2023) and is now under approval of the relevant technical committee CEN/TC 228/WG4. prEN 15316- 5:2023 comprises two methods applicable to the different types of water-based storage systems and related control system. Particularly interesting is the Method A, which considers the temperature stratification within the storage tank. In the Method A several assumptions, concerning the modelling of water flow through the tank, homogeneity of water temperature within the layer, conduction and convection between the layers, had to be implemented in the calculation procedure. Currently, there are no analyses in the open literature that validate the introduced assumptions. To address this, the present paper provides a comprehensive analysis of the method accuracy in the case of solar storage by comparison with the results obtained by CFD simulations. Furthermore, the influence of the temperature distributions within the storage tank obtained by 1-layer (Method B of prEN 15316- 5:2023), 4-layer, 5-layer model and CFD simulation on the obtained solar collector thermal efficiency is given. The results show are no significant differences in calculated thermal efficiencies, except for the 1-layer model where the differences are up to 8% relative to the CFD simulation.

Published
2023

2. Numerical modelling and analysis of heat transfer in solar storage tank

Author

Sinčić, Jakša, Dović, Damir, and Horvat, Ivan

Subjects
solarni spremnik, 2021 [prEN 15316-5], provođenje, conduction, slobodna konvekcija, solar storage tank, TEHNIČKE ZNANOSTI. Strojarstvo. Procesno energetsko strojarstvo, natural convection, TECHNICAL SCIENCES. Mechanical Engineering. Process Energy Engineering, ANSYS Fluent
Abstract

U sklopu diplomskog rada numerički je modelirana izmjena topline i strujanje vode unutar akumulacijskog spremnika solarnog toplovodnog sustava za pripremu potrošne tople vode i grijanje prostora. Dinamičke simulacije samog rada spremnika provedene su za odabrani period dana i režim korištenja u računalnom programu ANSYS Fluent. Zapremnina spremnika iznosila je 283,7 l, a odabrani učini izmjenjivača topline solarnog kruga te pomoćnog izvora prilagođeni su odabranom solarnom sustavu, dnevnoj potrošnji tople vode te potrebnoj energiji za grijanje prostora. Naglasak je dan analizi provođenja topline te slobodnoj konvekciji na temperaturnu raspodjelu u spremniku. Uspoređeni su rezultati simulacija s rezultatima proračuna temperaturne raspodjele u spremniku prema normi prEN 15316-5:2021, prilikom čega je spremnik podijeljen na više volumnih dijelova (segmenata). Zaključno, procijenjen je utjecaj rezultata simulacija i proračuna prema standardiziranoj proceduri na toplinsku učinkovitost solarnog kolektora u promatranom vremenskom periodu. In this work numerical modelling and analysis of heat transfer and water flow in solar storage tank was performed. Dynamic simulations of the tank in operating and heating mode for selected time of day, were carried out in computer software ANSYS Fluent. Capacity of stoarge tank is 283,7 l. Thermal output of heat exchanger for solar water heating and output of auxilliary heat exchanger were adapted for selected solar heating system, daily consumption of domestic hot water and required heating energy for space heating. Special attention was given to analysis of influence of conduction and natural convection on thermal stratification of storage tank. Simulation results were compared to ones acquired by using norm prEN 15316-5:2021. In doing so, storage tank was divided into multiple volume parts. Finally, impact of results of simulations and ones obtained by the norm on thermal efficiency of solar collector in selected time frame was assesed.

Published
2022

3. Transient Thermal Behavior of a Vertical Solar Storage Tank with a Mantle Heat Exchanger During No-Flow Operation

Author

A. Barzegar and A. A. Dehghan

Subjects
solar storage tank, thermal stratification, mantle heat exchanger, Mechanical engineering and machinery, TJ1-1570
Abstract

Transient thermal behavior of a vertical storage tank of a domestic solar heating system with a mantle heat exchanger has been investigated numerically in the charging mode. It is assumed that the tank is initially filled with uniform cold water. At an instant of time, the hot fluid from collector outlet is uniformly injected in the upper section of the mantle heat exchanger and after heat transfer with the fluid inside the tank, withdrawn from the bottom part of the heat exchanger. The conservation equations in the cylindrical coordinate and in axis-symmetric condition have been used according to the geometry under investigation. Governing equations have been discretized by employing the finite volume method and the SIMPLER algorithm has been used for coupling between momentum and pressure equations. The Low Reynolds Number (LRN) k −ω model is utilized for treating turbulence in the fluid. First, the transient thermal behavior of heat storage tank and the process of formation of thermal stratification in the heat storage tank were investigated. Then, the influence of Rayleigh number in the heat storage tank, Reynolds number in the mantle heat exchanger and vertical positioning of mantle on the flow and thermal fields and the formation of the thermal stratification was investigated. It is found that for higher values of Rayleigh number, a more suitable thermal stratification is established inside the tank. Also it is noticed that increasing the incoming fluid velocity through the mantle heat exchanger causes a faster formation of the thermal stratification. A superior thermal performance was achieved when the mantle heat exchanger is positioned at the middle height of the storage tank.

Published
2009

4. Thermal performance behavior of a domestic hot water solar storage tank during consumption operation

Author

Dehghan, A.A. and Barzegar, A.

Subjects
*SOLAR water heaters, *THERMODYNAMICS, *TURBULENCE, *REYNOLDS number, *HEAT exchangers, *ENERGY consumption, *FINITE volume method, *THERMAL analysis
Abstract

Abstract: Transient thermal performance behavior of a vertical storage tank of a domestic solar water heating system with a mantle heat exchanger has been investigated numerically in the discharge/consumption mode. It is assumed that the tank is initially stratified during its previous heat storing/charging operation. During the discharging period, the city cold water is fed at the bottom of the tank and hot water is extracted from its top outlet port for consumption. Meanwhile, the collector loop is assumed to be active. The conservation equations in the axis-symmetric cylindrical co-ordinate have been used and discretised by employing the finite volume method. The low Reynolds number (LRN) k − ω model is utilized for treating turbulence in the fluid. The influence of the tank Grashof number, the incoming cold fluid Reynolds number and the size of the inlet port of the heat storage tank on the transient thermal characteristics of the tank is investigated and discussed. It is found that for higher values of Grashof number, the pre-established thermal stratification is well preserved during the discharging operation mode. It is also noticed that in order to have a tank with a proper thermal performance and or have least mixing inside the tank during the consumption period, the tank inflow Reynolds number and or its inflow port diameter should be kept below certain values. In these cases, the storage tank is enabling to provide proper amount of hot water with a proper temperature for consumption purposes. [ABSTRACT FROM AUTHOR]

Published
2011
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5. Transient Thermal Behavior of a Vertical Solar Storage Tank with a Mantle Heat Exchanger during No-Flow Operation.

Author

Barzegar, A. and Dehghan, A. A.

Subjects
SOLAR heating equipment, HEAT exchangers, HEATING equipment, SOLAR thermal energy, STORAGE tanks, AERODYNAMICS, ENERGY storage, REFRIGERATION & refrigerating machinery, NUMERICAL analysis
Abstract

Transient thermal behavior of a vertical storage tank of a domestic solar heating system with a mantle heat exchanger has been investigated numerically in the charging mode. It is assumed that the tank is initially filled with uniform cold water. At an instant of time, the hot fluid from collector outlet is uniformly injected in the upper section of the mantle heat exchanger and after heat transfer with the fluid inside the tank, withdrawn from the bottom part of the heat exchanger. The conservation equations in the cylindrical coordinate and in axis-symmetric condition have been used according to the geometry under investigation. Governing equations have been discretized by employing the finite volume method and the SIMPLER algorithm has been used for coupling between momentum and pressure equations. The Low Reynolds Number (LRN) κ -ω model is utilized for treating turbulence in the fluid. First, the transient thermal behavior of heat storage tank and the process of formation of thermal stratification in the heat storage tank were investigated. Then, the influence of Rayleigh number in the heat storage tank, Reynolds number in the mantle heat exchanger and vertical positioning of mantle on the flow and thermal fields and the formation of the thermal stratification was investigated. It is found that for higher values of Rayleigh number, a more suitable thermal stratification is established inside the tank. Also it is noticed that increasing the incoming fluid velocity through the mantle heat exchanger causes a faster formation of the thermal stratification. A superior thermal performance was achieved when the mantle heat exchanger is positioned at the middle height of the storage tank. [ABSTRACT FROM AUTHOR]

Published
2009
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6. Numerical model for dynamic simulation of solar storage tank

Author

Beš, Borna and Dović, Damir

Subjects
Solar storage tank, degree of usability, collector, Solarni akumulacijski spremnik, temperatura, TEHNIČKE ZNANOSTI. Strojarstvo. Procesno energetsko strojarstvo, temperature, stupanj iskoristivosti, TECHNICAL SCIENCES. Mechanical Engineering. Process Energy Engineering, heat exchanger, kolektor, izmjenjivač topline
Abstract

Napravljen je numerički model dinamičke simulacije solarnog spremnika za zimski i ljetni režim rada koji uključuje period sa potrošnjom i bez potrošnje PTV-a. Dobiveni rezultati temperaturnog polja koje je izračunato u programu ANSYS Fluent su uspoređeni sa vrijednostima dobivenim proračunom prema normi HRN EN 15316-5:2017 (podjela na više kontrolnih volumena). Napravljena je analiza utjecaja na stupanj efikasnosti pločastog i vakuumskog kolektora u slučajevima kada se u proračun izmjene topline između radne tvari kolektorskog kruga i potrošne vode ulazilo sa vrijednostima PTV-a dobivenim računalnom simulacijom, prema normi i klasičnim termodinamičkim proračunom. A numerical model of a dynamic simulation of a solar storage tank was made, for winter and summer working mode, including a period with and witout consumption of DHW. The results of the temperature field calculated in the ANSYS Fluent program are compared with the values obtained by the calculation according to the HRN EN 15316-5: 2017 norm (division into multiple control volumes). An analysis was made of the impact on the degree of efficiency of the plate and vacuum collectors in cases when the calculation of the heat exchange between the heat transfer fluid and consumable water entered the DHW values obtained by computer simulation, according to the norm and the classical thermodynamic calculation.

Published
2019

7. Zásobník tepla solární soustavy

Author

Horák, Petr, Vranayová,, Zuzana, Hirš, Jiří, Horák, Petr, Vranayová,, Zuzana, and Hirš, Jiří

Abstract

Solární zásobník tepla představuje důležitý prvek solární soustavy. Umožňuje akumulaci přeměněné energie, a tím překrývá rozdíly mezi dodávkou a odběrem tepla mezi solární soustavou a odběrným místem. Vhodný návrh zásobníku je klíčový pro efektivní provoz a účinnost celé solární soustavy. Svou velikostí stanovuje množství využitelné energie a vlastní tepelné ztráty. Návrh solárního zásobníku vychází ze tří hypotéz. Solární pokrytí potřeby tepla, poměr akumulační kapacity zásobníku vzhledem ke kolektorové ploše a předpokladu, že objem solárního zásobníku odpovídá 1 - 2 násobné potřebě teplé vody. Smyslem této disertační práce je rozvinout poznání v oblasti navrhování solárních zásobníků tepla. Klade si za cíl stanovit pravidla pro návrh solárního zásobníku s pomocí numerického modelování a vycházejících z exaktních postupů založených na experimentálním měření a obecných výpočtech. Rovněž je zaměřena na ověření platnosti uvedených hypotéz a následného vyvození patřičných závěrů pro praxi a další možný výzkum. Numerický model obsahuje tři proměnné parametry, a to akumulační objem solárního zásobníku, plochu solárních kolektorů a počet uživatelů. Smyslem simulací je najít vzájemnou závislost těchto tří parametrů a na základě vzájemného ovlivnění, následně upravit návrh solárního zásobníku s ohledem k potřebě uživatele., The solar hot water storage tank is off great importance in the solar collector array. It allows transformed energy accumulation thus deals with the inconsistency between supply and demand. The suitable design of the storage tank can improve system efficiency. The storage capacity represents the balance between the amount of stored hot water and the tank's heat losses. The design of the storage capacity is based on three hypotheses. The coverage of hot water demand by solar energy, the ratio between storage capacity and solar thermal collector area and the prediction that the storage capacity corresponds to one- to twofold hot water demand. The purpose of this thesis is to share an understanding of the solar storage tanks design and to improve the design through numerical simulation, experimentations and general calculations. It also focuses on the confirmation of the used hypotheses and determination of the best way to design the solar storage tank for general practice and further potential discussions. The simulation model has three variables – the storage capacity, collector area and the number of occupants. The intent is to find the interdependence of these three variables. The purpose of the simulations is to modify the design of the solar tank based on the mutual influence of studied parameters. The modifications are performed based on the users' needs.

8. Zásobník tepla solární soustavy

Author

Horák, Petr, Vranayová,, Zuzana, Hirš, Jiří, Horák, Petr, Vranayová,, Zuzana, and Hirš, Jiří

Abstract

Solární zásobník tepla představuje důležitý prvek solární soustavy. Umožňuje akumulaci přeměněné energie, a tím překrývá rozdíly mezi dodávkou a odběrem tepla mezi solární soustavou a odběrným místem. Vhodný návrh zásobníku je klíčový pro efektivní provoz a účinnost celé solární soustavy. Svou velikostí stanovuje množství využitelné energie a vlastní tepelné ztráty. Návrh solárního zásobníku vychází ze tří hypotéz. Solární pokrytí potřeby tepla, poměr akumulační kapacity zásobníku vzhledem ke kolektorové ploše a předpokladu, že objem solárního zásobníku odpovídá 1 - 2 násobné potřebě teplé vody. Smyslem této disertační práce je rozvinout poznání v oblasti navrhování solárních zásobníků tepla. Klade si za cíl stanovit pravidla pro návrh solárního zásobníku s pomocí numerického modelování a vycházejících z exaktních postupů založených na experimentálním měření a obecných výpočtech. Rovněž je zaměřena na ověření platnosti uvedených hypotéz a následného vyvození patřičných závěrů pro praxi a další možný výzkum. Numerický model obsahuje tři proměnné parametry, a to akumulační objem solárního zásobníku, plochu solárních kolektorů a počet uživatelů. Smyslem simulací je najít vzájemnou závislost těchto tří parametrů a na základě vzájemného ovlivnění, následně upravit návrh solárního zásobníku s ohledem k potřebě uživatele., The solar hot water storage tank is off great importance in the solar collector array. It allows transformed energy accumulation thus deals with the inconsistency between supply and demand. The suitable design of the storage tank can improve system efficiency. The storage capacity represents the balance between the amount of stored hot water and the tank's heat losses. The design of the storage capacity is based on three hypotheses. The coverage of hot water demand by solar energy, the ratio between storage capacity and solar thermal collector area and the prediction that the storage capacity corresponds to one- to twofold hot water demand. The purpose of this thesis is to share an understanding of the solar storage tanks design and to improve the design through numerical simulation, experimentations and general calculations. It also focuses on the confirmation of the used hypotheses and determination of the best way to design the solar storage tank for general practice and further potential discussions. The simulation model has three variables – the storage capacity, collector area and the number of occupants. The intent is to find the interdependence of these three variables. The purpose of the simulations is to modify the design of the solar tank based on the mutual influence of studied parameters. The modifications are performed based on the users' needs.

9. Zásobník tepla solární soustavy

Author

Horák, Petr, Vranayová,, Zuzana, Hirš, Jiří, Horák, Petr, Vranayová,, Zuzana, and Hirš, Jiří

Abstract

Solární zásobník tepla představuje důležitý prvek solární soustavy. Umožňuje akumulaci přeměněné energie, a tím překrývá rozdíly mezi dodávkou a odběrem tepla mezi solární soustavou a odběrným místem. Vhodný návrh zásobníku je klíčový pro efektivní provoz a účinnost celé solární soustavy. Svou velikostí stanovuje množství využitelné energie a vlastní tepelné ztráty. Návrh solárního zásobníku vychází ze tří hypotéz. Solární pokrytí potřeby tepla, poměr akumulační kapacity zásobníku vzhledem ke kolektorové ploše a předpokladu, že objem solárního zásobníku odpovídá 1 - 2 násobné potřebě teplé vody. Smyslem této disertační práce je rozvinout poznání v oblasti navrhování solárních zásobníků tepla. Klade si za cíl stanovit pravidla pro návrh solárního zásobníku s pomocí numerického modelování a vycházejících z exaktních postupů založených na experimentálním měření a obecných výpočtech. Rovněž je zaměřena na ověření platnosti uvedených hypotéz a následného vyvození patřičných závěrů pro praxi a další možný výzkum. Numerický model obsahuje tři proměnné parametry, a to akumulační objem solárního zásobníku, plochu solárních kolektorů a počet uživatelů. Smyslem simulací je najít vzájemnou závislost těchto tří parametrů a na základě vzájemného ovlivnění, následně upravit návrh solárního zásobníku s ohledem k potřebě uživatele., The solar hot water storage tank is off great importance in the solar collector array. It allows transformed energy accumulation thus deals with the inconsistency between supply and demand. The suitable design of the storage tank can improve system efficiency. The storage capacity represents the balance between the amount of stored hot water and the tank's heat losses. The design of the storage capacity is based on three hypotheses. The coverage of hot water demand by solar energy, the ratio between storage capacity and solar thermal collector area and the prediction that the storage capacity corresponds to one- to twofold hot water demand. The purpose of this thesis is to share an understanding of the solar storage tanks design and to improve the design through numerical simulation, experimentations and general calculations. It also focuses on the confirmation of the used hypotheses and determination of the best way to design the solar storage tank for general practice and further potential discussions. The simulation model has three variables – the storage capacity, collector area and the number of occupants. The intent is to find the interdependence of these three variables. The purpose of the simulations is to modify the design of the solar tank based on the mutual influence of studied parameters. The modifications are performed based on the users' needs.

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