Direct optimal control of valve openings in heat exchanger networks and experimental validations

Wang, Yifei; Chen, Qun

doi:10.1016/j.ijheatmasstransfer.2015.06.064

Cited by 24 publications

(8 citation statements)

References 18 publications

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“…The equation of continuity declares that the mass flow rate in each hot‐water loop is the same, which makes the characteristic parameters constant (right side in Figure ). Under slight flow rate variation, the pressure head H caused by the pipeline is as follows:

H_{i} = h_{si} + d_{hi} {\overset{m}{true}}_{i}^{2},

where h s stands for the static pressure head, d h is the characteristic parameter of the pipeline,

\overset{m}{true}

is the mass flow rate, and i is the number of hot‐water loop.…”

Section: Physical and Mathematical Models Of A Compound Series‐parallmentioning

confidence: 99%

“…For the characteristic parameters of each pump, the following experimental steps can identify their values. 30,31 First, run the pump under the rated frequency, 50 Hz, with a certain valve opening, 100%, at steady state for 10 minutes. Secondly, repeat the first step with a series of valve opening, 80%, 60%, 50%, 40%, 30%, and 20%, respectively.…”

Section: Characteristic Parametersmentioning

confidence: 99%

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Operation optimization of variable frequency pumps in compound series‐parallel heat transfer systems based on the power flow method

Shao

Chen

Zhang

2018

Energy Science & Engineering

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The optimal match of multiple operation parameters in heat transfer systems (HTSs) is the key to trade‐off heat transfer and flow resistance for energy conservation. For a compound series‐parallel HTS, this study applies the power flow model and the driving‐resistance model to build the heat transfer and fluid flow constraints of the whole system directly, instead of individual components. Utilizing these constraints together with the Lagrange multiplier method offers the optimal operating frequencies of each variable frequency pumps (VFP) with the minimum pumping power consumptions under different heat loads. Operating the experiment platform with the optimized parameters shows that the heat load increment in parallel branches only needs to increase the operating frequency of VFP in the related hot‐water loop, whereas the heat load increment in series branches needs to increases the operating frequencies of VSPs in both cold‐water and the corresponding hot‐water loops. When the heat load varies from 10 to 11 kW in the parallel branch, the downstream, and the upstream of the series branch, the total pumping power consumptions of all VFPs increase by 19.45%, 43.86%, and 39.99%, respectively. It means assigning the additional heat load in the parallel branch is more energy efficient.

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H_{i} = h_{si} + d_{hi} {\overset{m}{true}}_{i}^{2},

where h s stands for the static pressure head, d h is the characteristic parameter of the pipeline,

\overset{m}{true}

is the mass flow rate, and i is the number of hot‐water loop.…”

Section: Physical and Mathematical Models Of A Compound Series‐parallmentioning

confidence: 99%

Section: Characteristic Parametersmentioning

confidence: 99%

Operation optimization of variable frequency pumps in compound series‐parallel heat transfer systems based on the power flow method

Shao

Chen

Zhang

2018

Energy Science & Engineering

Self Cite

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“…As it can be seen, the inner loop of the algorithm (lines 5-11) tests the closeness (line 6) of the current operating point, along the main diagonal, and the points to the right of the angle-matrix ⌊ ⌋ × . Our proposal is to introduce another inner loop which would test the closeness of the current operating point and the points on the left side on the same row of the angle-matrix (Algorithm 2: lines [12][13][14][15][16][17][18].…”

Section: Multilinear Modelmentioning

confidence: 99%

“…. , (4) for = 1 : compression subregion of a small range(14) In the middle of choose operating point ( , )Algorithm 1: Algorithmic view of the Included Angle Dividing method.…”

mentioning

confidence: 99%

Multilinear Model of Heat Exchanger with Hammerstein Structure

Pršić¹,

Nedić²,

Filipović³

et al. 2016

Journal of Control Science and Engineering

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The multilinear model control design approach is based on the approximation of the nonlinear model of the system by a set of linear models. The paper presents the method of creation of a bank of linear models of the two-pass shell and tube heat exchanger. The nonlinear model is assumed to have a Hammerstein structure. The set of linear models is formed by decomposition of the nonlinear steady-state characteristic by using the modified Included Angle Dividing method. Two modifications of this method are proposed. The first one refers to the addition to the algorithm for decomposition, which reduces the number of linear segments. The second one refers to determination of the threshold value. The dependence between decomposition of the nonlinear characteristic and the linear dynamics of the closed-loop system is established. The decoupling process is more formal and it can be easily implemented by using software tools. Due to its simplicity, the method is particularly suitable in complex systems, such as heat exchanger networks.

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“…The development of heat pump (HP) technologies has made it possible to use a variety of renewable energy sources as heating and cooling sources for buildings such as solar energy, geothermal energy and so on. To meet the thermal and cooling loads of buildings, the use of renewable energy that is available close to the buildings has also been investigated using various types of heat pump systems [4][5][6][7][8][9][10][11]. For example, the so-called solarassisted ground source heat pump system (SAGSHPS), which can couple geothermal and solar thermal energies, has been proposed and its feasibility and performance have been examined.…”

Section: Introductionmentioning

confidence: 99%

Experimental performance analysis of a multiple-source and multiple-use heat pump system: winter field experiment and heating operation performance evaluation

et al. 2019

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We herein report the development of a distributed heat pump system that can utilize a variety of renewable energy sources to meet different building heating and cooling demands (i.e., a multiple source and multiple use heat pump system, MMHP). In this system, a water circulating loop is used to connect ground heat exchangers, a unique sky-source heat pump, and various heat pumps for heating and cooling purposes to form a thermal network within a building. This distribution increases the flexibility of the system and allows an improved matching of supply and demand. To evaluate the system performance, an experimental house was constructed, and a winter field experiment was conducted. We found that the reported heat pump for floor heating achieved a stable operation with a high coefficient of performance of ~11.5, while the heat collecting operation performance of the sky-source heat pump varied significantly depending on the amount of solar radiation and the outside air temperature. Finally, since the sky-source heat pump contributes to an improvement in the whole system performance, it appears that there is still room for improved regarding the whole system performance by adjusting the operating and control strategy.

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Direct optimal control of valve openings in heat exchanger networks and experimental validations

Cited by 24 publications

References 18 publications

Operation optimization of variable frequency pumps in compound series‐parallel heat transfer systems based on the power flow method

Operation optimization of variable frequency pumps in compound series‐parallel heat transfer systems based on the power flow method

Multilinear Model of Heat Exchanger with Hammerstein Structure

Experimental performance analysis of a multiple-source and multiple-use heat pump system: winter field experiment and heating operation performance evaluation

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