Near Optimal Receding Horizon Control of Thermal Energy Storage

2021 ◽  
pp. 1-13
Author(s):  
Omer Ahmed Qureshi ◽  
Peter R. Armstrong
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Energy Savings ◽  
Search Algorithm ◽  
Cost Savings ◽  
Weather Conditions ◽  
Receding Horizon Control ◽  
Receding Horizon ◽  
Favorable Weather

Abstract Efficient plant operation can be achieved by properly loading and sequencing available chillers to charge and discharge a thermal energy storage (TES) reservoir at optimal rates and times. TES charging sequences are often determined by heuristic rules that typically aim to reduce utility costs under time of use rates. However, such rules of thumb may result in significantly sub optimal performance on somedays. Rigorous optimization, on the other hand, is computationally expensive and can be unreliable as well if not carefully implemented. Receding Horizon Control (RHC) using the novel finite search algorithm is reliable and can reach ~80% of achievable energy efficiency and/or peak shifting capacity has been our target. A novel algorithm is developed to reliably achieve near optimal control for charging the stratified sensible cool storage reservoir of a chiller plant. The algorithm provides a constant COP (or cost per ton-hour) for 24-hr dispatch plan under which chillers operate during most favorable weather conditions. Analysis of four hot climates, ranging from humid to dry, indicates 2.4~2.6% energy savings under a flat electricity rate relative to the same plant operating without TES. Annual cost savings from 6% to 9% was found for electricity billed under a simple (10am-10pm) time-of-use rate with no demand charge and no ratchet component.

scholarly journals Improvement of operation of steam cushion system for sensible thermal energy storage

2019 ◽  
Vol 116 ◽  
pp. 00107
Author(s):  
Ryszard Zwierzchowski
Keyword(s):  
Heat Flux ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Energy Savings ◽  
Operating Conditions ◽  
Production Costs ◽  
Technical Solution ◽  
Atmospheric Air ◽  
Suction Pipe

The paper contains a method for improvement of operation of steam cushion system including its energy savings analyses, for a Thermal Energy Storage (TES) tank. Energy savings analyses were performed using operational data from selected Combined Heat and Power plants, which supply heat to large cities in Poland and are furnished with the TES. The role of the steam cushion system in the TES tank is to prevent the stored water against absorbing oxygen from atmospheric air. In the TES tank, which is a non-pressure tank, oxygen from atmospheric air could penetrate to the network water through the surge chamber and safety valves. The steam pressure under the roof is generated from technological steam injected under the roof. Energy savings in the steam cushion system are generated by using an appropriate technical solution for the upper orifice and suction pipe for circulation water, i.e., to make it movable through the use of pontoons. An isolating buffer layer is created at the top of the tank with very small convective and turbulent heat transport, which causes limited heat transfer from steam bed to the stored water in the tank. This results in heat flux of approximately 10% of the heat flux that occurs in the typical technical solution of the upper orifice and suction pipe for circulation water in the TES tank. This technology offers great opportunities to improve the operating conditions of District Heating System, cutting energy production costs and emissions of pollutants to the atmosphere.

Near Optimal Model Predictive Control of Thermal Energy Storage

2020 ◽  
Author(s):  
O. A. Qureshi ◽  
P. R. Armstrong
Keyword(s):  
Energy Storage ◽  
Model Predictive Control ◽  
Predictive Control ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
High Reliability ◽  
Operating Cost ◽  
Weather Conditions ◽  
Preliminary Evaluation ◽  
Novel Algorithm

Abstract Efficient plant operation can be achieved by properly loading and sequencing available chillers to charge a thermal energy storage (TES) reservoir. TES charging sequences are often determined by heuristic rules that typically aim to reduce utility costs under time of use rates. However, such rules of thumb are in most cases far from optimal even for this task. Rigorous optimization, on the other hand, is computationally expensive and can be unreliable as well if not carefully implemented. Model-predictive control (MPC) that is reliable, as well as effective, in TES application must be developed. The goal is to develop an algorithm that can reach ∼80% of achievable energy efficiency and peak shifting capacity with very high reliability. A novel algorithm is developed to reliably achieve near optimal control for charging cool storage in chiller plants. Algorithm provides a constant COP (or cost per ton-hour) for 24-hr dispatch plan at which plant operates during most favorable weather conditions. Preliminary evaluation of this novel algorithm has indicated up to 6% improvement in plant annual operating cost relative to the same plant operating without TES. TOU rate used in both cases charges 7.4cents/kWh during off peak hours and 9.8cents/kWh during peak hours (Peak hours are 10 am to 10 pm).

Investigation of Conducting Pins in Sphere Filled with Phase Change Material for Enhancing Heat Transfer in Thermal Energy Storage

2012 ◽  
Vol 472-475 ◽  
pp. 1693-1697 ◽  
Author(s):  
Nasrul Amri Mohd Amin ◽  
Frank Bruno ◽  
Martin Belusko
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Phase Change Material ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Energy Savings ◽  
Packed Bed ◽  
Plastic Sphere ◽  
Change Material

The utilisation of phase change material (PCM) for thermal energy storage (TES) can significantly enhance the energy savings achievable with renewable thermal systems. Sphere based packed bed systems have been used as TES for many years. However, due to the thermal resistance within these systems, the heat transfer is limited and not all the PCM can be used effectively. This study focuses on heat transfer enhancement options for single PCM sphere in a TES system. An experimental investigation has been conducted using water as the PCM. The thermal performance of plain plastic sphere containing PCM has been compared to plastic sphere encapsulated with conducting pins. The heat transfer rate of the sphere with conducting pins was more than 34% that of the sphere without pins.

Building Energy Management: Co-Generation Coupling With Thermal Energy Storage

2002 ◽  
Author(s):  
K. H. Khan ◽  
M. G. Rasul ◽  
M. M. K. Khan
Keyword(s):  
Energy Consumption ◽  
Energy Storage ◽  
Energy Management ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Energy Savings ◽  
Peak Demand ◽  
Building Energy Management ◽  
Demand Reduction ◽  
Chilled Water

This paper is concerned with the feasibility study and evaluation of an energy savings opportunity in buildings energy management using co-generation coupling with thermal energy storage. Both the technical and economical feasibility is presented first for the co-generation and then compared with the co-generation using thermal energy storage. On-site co-generation with double effect absorption chiller provides a potential of at least 13% peak demand reduction and about 16% savings in energy consumption. It provides an internal rate of return (IRR) greater than 21% but saving potential is limited by the low demand of co-generated chilled water within the community of the institution. Thermal energy storage coupling with co-generation offers a simple and economically more attractive approach for maximizing the utilization of co-generated chilled water and shows 23% reduction in peak demand and 21% savings in energy consumption. It provides higher IRR, greater than 25%.

scholarly journals A Parametric Study of a Solar-Assisted House Heating System with a Seasonal Underground Thermal Energy Storage Tank

2020 ◽  
Vol 12 (20) ◽  
pp. 8686 ◽  
Author(s):  
Le Minh Nhut ◽  
Waseem Raza ◽  
Youn Cheol Park
Keyword(s):  
Mathematical Model ◽  
Energy Storage ◽  
South Korea ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage Tank ◽  
Fossil Fuels ◽  
Weather Conditions ◽  
Heating System ◽  
Thickness Effect

The requirement for energy is increasing worldwide as populations and economies develop. Reasons for this increase include global warming, climate change, an increase in electricity demand, and paucity of fossil fuels. Therefore, research in renewable energy technology has become a central topic in recent studies. In this study, a solar-assisted house heating system with a seasonal underground thermal energy storage tank is proposed based on the reference system to calculate the insulation thickness effect, the collector area, and an underground storage tank volume on the system performance according to real weather conditions at Jeju Island, South Korea. For this purpose, a mathematical model was established to calculate its operating performance. This mathematical model used the thermal response factor method to calculate the heat load and heat loss of the seasonal underground thermal energy storage tank. The results revealed that on days with different weather conditions, namely, clear weather, intermittent clouds sky, and overcast sky, the obtained solar fraction was 45.8%, 17.26%, and 0%, respectively. Using this method, we can save energy, space, and cost. This can then be applied to the solar-assisted house heating system in South Korea using the seasonal underground thermal energy storage tank.

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