Thermal Energy Storage Optimization in Shopping Center Buildings

Altuntop

2019

Energy Storage

The storage tank has great impact on the performance of ice thermal energy storage (ITES) system. Previous researches show that enhanced temperature gradient in the tank improves the thermal performance of system. This study deals with the investigation for determining the effect of using graded porosity in the storage tank of encapsulated ITES system. In this study, it was researched that the effects of uniform, two‐graded, and three‐graded porosities inside the storage tank. Energy equation in porous medium was solved analytically to determine the centerline temperature changing in the tank. At the end of study, it was found that the lower porosity supplied higher thermal performance. However, lower porosity requires higher tank volume. Graded porosity provided the almost equal thermal performance with lower uniformly distributed porosity, although it had a higher porosity. Energy efficiency values were very high and changed between 95.23% and 99.98% in all porosity structure and working conditions. On the contrary to the energy efficiency values, exergy efficiency values were changed over a wider range between 35.80% and 88.71%. The highest exergy efficiency of 88% was seen in ε = 0.4 uniform porosity. Also, (ε1 = 0.4, ε2 = 0.5) two‐graded porosity and (ε1 = 0.4, ε2 = 0.5, ε3 = 0.6) three‐graded porosity provided higher exergy efficiency. While exergy efficiency increased with increasing heat transfer fluid (HTF) flow rate, decreased with decreasing HTF inlet temperature.

Section: Introductionmentioning

confidence: 99%

Investigation of the effect of using graded porosity on the thermal performance of the encapsulated ice thermal energy storage tank

Altuntop

2019

Energy Storage

“…They emphasized that although the ITES system might increase electricity consumption, they decreased the cooling cost. ITES systems have a significant potential to reduce cooling costs in all climate zones, depending on the storage capacity, how stored energy is used, and the type of system …”

Section: Introductionmentioning

confidence: 99%

“…ITES systems have a significant potential to reduce cooling costs in all climate zones, depending on the storage capacity, how stored energy is used, and the type of system. [10][11][12][13][14] The storage tank has a great impact on the thermal performance of the ITES system. For an ITES system, increasing thermal performance increases the economic performance of the system.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of thermal performance of geometrically modified spherical ice capsules during the discharging period

2019

Int J Energy Res

Summary Ice thermal energy storage (ITES) is a significant option for shifting cooling load from peak hours to off‐peak hours in order to reduce the cooling cost and equipment capacity. Encapsulated ITES system is one of the most preferred types of ITES systems, because it is easier to apply and has lower initial cost than other types of ITES systems. Capsule geometries have great impact on the thermal performance of the encapsulated ITES system. Spherical capsules are widely used in the application because they provide better thermal performance due to the ratio of its volume to its surface area. Also, modified capsule geometries are used for increasing the thermal performance of the ITES system. This paper focuses on a numerical study in order to determine the effect of the geometrically modified spherical capsule on the thermal performance during the discharging period. Seven geometrically modified spherical capsules were investigated and compared with the ordinary spherical capsule. The FLUENT 17.1 code was used for numerical analyses. At the end of the study, it was found that geometrically modified capsules provided higher thermal performance than an ordinary spherical capsule in the equal capsule volume. Capsule D provided the longest discharging period of 2118 seconds, when VHTF, in = 0.001 m/s and THTF,in = 275.5 K. The lowest discharging time of 464 seconds was obtained with Capsule A, when VHTF, in = 0.01 m/s and THTF, in = 283 K. Among the studied modified capsules, Capsule F performed the worst thermal performance. Energy efficiency values were high, and they did not give comparable difference between the capsule models and working conditions. While all exergy values were 98.50% and higher, exergy efficiency values changed between 85.12% and 51.91%. Exergetically, Capsule D provided the best thermal performance during the discharging period.

“…Effect of the 40% partial storage on cooling cost for a commercial building has been investigated by Beghi et al They have emphasized that energy and exergy efficiencies should be considered during the ITES control strategies. Biyanto et al have found that initial investment and electricity costs can be reduced up to 20% and 11% with cooled water storage system. Yan et al have investigated the effect of cooled water cold storage system on cooling cost for a 2000‐m 2 residential building in Beijing, China.…”

Section: Introductionmentioning

confidence: 99%

Effect of encapsulated ice thermal storage system on cooling cost for a hypermarket

Altuntop

2018

Int J Energy Res

Summary Hypermarkets have high cooling load, because of high heat gains from environment and high people circulation. So the cooling cost of hypermarkets is generally so high. Cooling cost can be reduced by cold thermal energy storage systems. The aim of the present study is to determine the effect of different ice thermal storage system (ITES) utilization strategies on cooling cost for a hypermarket. Hypermarket is located in Ankara, Turkey. Daily peak cooling load of the hypermarket is 8332 kWh. To decrease to cooling cost, encapsulated ITES has been integrated to the hypermarket air conditioning system. Ice thermal storage system utilization strategies have great impact on the economic performance of the system. So, in this study, the effect of different ice storage strategies on the cooling cost was investigated. Results presented in the term of saving amount and payback period. At the end of study, it was found that the cooling cost decreased with the increasing storage capacity. Also, to increase saving amount, the stored energy should be used in electricity peak hour as much as possible. Load leveling and partial storage for peak hours strategies have shown that how the stored energy is used has as great impact as storage capacity on the economic performance of ITES, because load leveling and partial storage for peak hours strategies have performed better performance in the terms of payback period and profit amount at the end of 10 years than ordinary partial storage strategies at the same storage capacity. The highest profit at the end of 10 years is 1 450 000 USD and seen in full storage strategy. The lowest profit at the end of 10 years is 185 000 USD and seen in 10% partial storage. Also, while the shortest payback period is seen in both load leveling and 10% partial storage strategies with about 1.5 years, the longest payback period is seen in full storage strategy with about 3.1 years.