Function method for dynamic temperature simulation of district heating network

Zheng, Jiayu; Zhou, Zhigang; Zhao, Junming; Wang, Jinda

doi:10.1016/j.applthermaleng.2017.05.083

Cited by 59 publications

(26 citation statements)

References 15 publications

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“…Authors of [11] develop new so-called function method for the evaluation of thermal transients in DH grids. The method is based on the insertion of a Fourier series into the simplified Partial Differential Equation (PDE) of the fluid and solid regions of the circular pipe to derive the relationship between inlet and outlet temperature.…”

Section: Introductionmentioning

confidence: 99%

Performant and Simple Numerical Modeling of District Heating Pipes with Heat Accumulation

2019

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This paper compares approaches for accurate numerical modeling of transients in the pipe element of district heating systems. The distribution grid itself affects the heat flow dynamics of a district heating network, which subsequently governs the heat delays and entire efficiency of the distribution. For an efficient control of the network, a control system must be able to predict how “temperature waves” move through the network. This prediction must be sufficiently accurate for real-time computations of operational parameters. Future control systems may also benefit from the accumulation capabilities of pipes. In this article, the key physical phenomena affecting the transients in pipes were identified, and an efficient numerical model of aboveground district heating pipe with heat accumulation was developed. The model used analytical methods for the evaluation of source terms. Physics of heat transfer in the pipe shells was captured by one-dimensional finite element method that is based on the steady-state solution. Simple advection scheme was used for discretization of the fluid region. Method of lines and time integration was used for marching. The complexity of simulated physical phenomena was highly flexible and allowed to trade accuracy for computational time. In comparison with the very finely discretized model, highly comparable transients were obtained even for the thick accumulation wall.

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Section: Introductionmentioning

confidence: 99%

Performant and Simple Numerical Modeling of District Heating Pipes with Heat Accumulation

2019

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“…A method for calculating the time delay of the network was presented by Jie, et al [11] who using physical and mathematical models, proved that in the case of a single straight pipe with constant pipe diameter, the time delay was approximately equal to the flow time of the heat medium. Zheng [12] proposed a new physical method (function method) and corresponding dynamic temperature simulation computer code to analyze the thermal dynamic characteristics of the district heating network, focusing on the dynamic temperature distribution. The results showed that the function method could be recommended to simulate the dynamic temperature of district heating network accurately and quickly for efficient system performance.…”

Section: Introductionmentioning

confidence: 99%

An Influencing Parameters Analysis of District Heating Network Time Delays Based on the CFD Method

Zhao

2019

Energies

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With the expansion of cities, district heating (DH) networks are playing an increasingly important role. The energy consumption due to the time delay caused by the transport of the medium in the DH network is enormous, especially in large networks. The study of time delay is necessary for the operation and optimization of DH networks. Compared with previous studies of constant flow rates and ideal pipeline (without regard to branches, elbows, variable pipe diameters, etc), this paper simulates a DH network in Tianjin University, China, by establishing the actual engineering model in a Computational Fluid Dynamics (CFD) method to analyze the time delay. The CFD model has great advantages in terms of computational cost and application range compared to theoretical calculations. The peak-valley method was used to verify the correctness of the time delay simulation model. Results show that the time delay calculated by the CFD model is consistent with the actual time delay obtained from the measured data. Based on this model, the parameters that affect the time delay are furtherly analyzed. Four key parameters, including flow rate, pipe length, pipe diameter, and water supply temperature are summarized. The results show that the flow rate, pipe length and pipe diameter have a great influence on the time delay of the DH network, while the temperature has little effect on the time delay. The time delay of the DH network system has a significant impact and can provide services for optimal control of the system.

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“…The scale of these systems varies from building facilities to a complete city. The management of DH networks has long been considered to be a static problem since operative control is kept to a minimum and the network is reconfigured only occasionally [1][2][3]. This model of design and operation is proving to be outdated [4].…”

Section: Introductionmentioning

confidence: 99%

“…In the literature two main approaches have been pursued for the modeling of DH, the black box models and the physical models [2]. The former are data-driven models that consider only the input and outputs of the system and are known for their speed but low accuracy on highly dynamic systems.…”

Section: Introductionmentioning

confidence: 99%

“…Other methods have been proposed that have gains in speed, accuracy or level of detail. The Function Method, presented in [2], considers the mass flow rate, the losses and the inertia and obtains the analytical solution to the transient energy equation by using the expansion of Fourier series. This method proves to be 37% faster than the Node Method while being more accurate during rapid changes in the temperature.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Modified finite volumes method for the simulation of dynamic district heating networks

Schwarz

Mabrouk

Silva

et al. 2019

Energy

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District Heating (DH) networks are getting closer to the concept of "Smart Grids" to deal with the contribution of new technologies and paradigms like Renewable Energy Sources, Distributed Generation and Storage, and Low-Temperature District Heating. This requires good anticipation of the system's dynamics with the objective of improving control. This work proposes a model based on the Finite Volumes method for anticipating the dynamics in DH systems. Its application to branched network topologies gives the delay between the change in the settings at the generation points and the time they are perceived by the different substation in the network, which is a prerequisite for system design, operation planning and optimal control. The model is tested in a 6 Node branched network with the main topology elements being represented (junctions, splits, etc.); real demand data is used at the consumption nodes. A comparison between the model developed by the authors and the existing Finite Volumes method is also presented for the proposed topology. These results shed light on the needs and opportunities in DH, mainly for ICT implementation, energy storage location and management, and enhanced control in the smart energy networks context.

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Function method for dynamic temperature simulation of district heating network

Cited by 59 publications

References 15 publications

Performant and Simple Numerical Modeling of District Heating Pipes with Heat Accumulation

Performant and Simple Numerical Modeling of District Heating Pipes with Heat Accumulation

An Influencing Parameters Analysis of District Heating Network Time Delays Based on the CFD Method

Modified finite volumes method for the simulation of dynamic district heating networks

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