Horizontal Cylindrical Storage Research Articles

Seismic vulnerability assessment of spherical and horizontal-cylindrical storage tanks through finite element analyses and observational data

Storage tanks are structures widely employed in various chemical and petroleum industries for the storage of liquids and gases. These structures, which store flammable and explosive substances, can lead to events such as fire and explosion in the event of any hazardous situation. Such accidents can have adverse effects on human life, facilities, the economy, and the environment. Earthquakes, as a natural threat affecting all structures, also trigger events like fire and explosion in storage tanks. Therefore, the assessment of seismic risks for storage tanks, the prediction of damage, is crucial for both existing and newly constructed tanks. In this study, the seismic behaviors of spherical and horizontal cylindrical storage tanks were investigated based on observational and finite element analysis data. Fragility analyses of tanks were conducted considering several commonly used statistical approaches, and fragility curves were derived. By using fragility curves, the probability of structural damage due to earthquakes is observed as a function of ground motion parameters. These curves express the likelihood of reaching or exceeding a pre-determined damage state under seismic effects for the considered type of structure. They are developed to predict potential damage during earthquakes and are outputs of seismic risk assessments. Fragility curves are utilized as indicators to determine physical damage during both the main shock and lower-intensity aftershocks. They can provide insights into whether the structure can be reused after earthquakes. Additionally, they are employed to reduce economic losses and casualties in the face of seismic events. For these reasons, fragility curves are essential statistical tools for decision-making both before and after earthquakes.

Study on the melting dynamics of latent heat storage for various orientations, shell shapes, and eccentricity

In this research, the melting dynamics of NaNO2-based shell and tube-type latent heat storage are comparatively evaluated for various orientations of the storage (vertical and horizontal) and various shell shapes (cylindrical and frustum). Furthermore, the performance of the various storage configuration is compared with the horizontal cylindrical storage having bottom eccentricity in the heat transfer fluid passage. The enthalpy porosity method is incorporated to evaluate the thermal behaviour of the various storage configurations. A total reduction in the charging time is noticed as 18.42% and 34.21%, respectively, in the vertical frustum storage and horizontal cylindrical storage unit as compared to the vertical cylindrical storage unit. It is revealed that the accelerated melt front movement along the entire length of the storage improves the heat transfer in the horizontal cylindrical storage units. At 250 min of the charging cycle, horizontal cylindrical storage stores 100% of the targeted energy, while vertical cylindrical storage and vertical frustum storage store only 80% and 90%, respectively, of the targeted energy storage capacity. The enlarged melt front developed by the downward eccentric shifting of the inner heat transfer fluid passage further augments the heat transfer rate in the horizontal cylindrical storage. The total charging time of the horizontal cylindrical storage is noticed as 250 min, 230 min, 210 min, 200 min, and 190 min for bottom eccentric locations of 0 mm, 5 mm, 10 mm, 15 mm, and 20 mm, respectively. A 20 mm shifting of the inner tube results in a maximum curtailment of 24% in the charging time of the storage than the horizontal cylindrical storage having a concentric inner tube.

Numerical and experimental study of inlet-outlet locations effect in horizontal storage tank of solar water heater

A good thermal stratification in the storage tank of the solar water heater is an effective process to increase the efficiency of the solar system. This study investigates numerically and experimentally the effect of varying the inlet and outlet location of the fluid in the horizontal cylindrical storage tank for optimizing the thermal stratification process. While the location of the outlet fixed, the inlet was varied and vice versa. A model based on an energy balance was introduced. Simulated temperature profile for each case was compared with the experiment, which indicated maximum deviation of up to 7%. In an experimental case at 1 p.m., the three average temperatures on the vertical line in the middle of the tank recorded 49.9, 48.7, and 48.4 °C with an average of 49 °C while the simulation result was obtained 47.1 °C. Hence, the experimental and numerical temperature difference of 1.9 °C with the error 3.9% was noticed. An appropriate location for the hot water inlet resulted in better thermal stratification in the storage tank. In addition, an appropriate location for the cold water outlet resulted a better collector efficiency, which both increased the performance of solar water heater system.

Three-dimensional analysis and investigation of the thermal and hydrodynamic behaviors of cylindrical storage tanks

A numerical analysis of the three-dimensional temperature and velocity fields in horizontal cylindrical storage tanks was performed. The phenomena of laminar natural convection and vertical stratification of temperature were considered. The developed three-dimensional transient computing code solves the equations of energy and momentum through the finite volume method. The simulation of fluid cooling process inside the tank showed the formation of stratified temperature profiles that matched those obtained experimentally. Based on several simulations, a correlation was proposed for determining the degree of thermal stratification inside the tank regarding thermal and geometrical parameters. From this correlation, an expression was proposed to predict the fluid temperature profiles along the time. This information is very important in many applications, such as in thermosiphon solar water heating systems, where the global efficiency of the system increases with the thermal stratification degree of the working fluid. Another case studied considered that the tank was connected to solar collectors, aiming at investigating the influence of the inlet jet position with and without a baffle plate on the preservation of the thermal stratification. Results showed that the baffle plate modified the velocity and temperature fields close to the inlet jet, allowing a better thermal stratification. Also the suitable choice of the inlet jet position allowed the formation of a more effective thermal stratification. Some other aspects of the internal dynamics of this kind of storage tank are presented and discussed. For the cases studied, the inlet jet next to the top led to a greater thermal stratification. However, it was verified that when the inlet jet temperature remains constant for a long period of time, and thus its temperature approaches the temperature of the water inside the tank, for the same height, the temperature profiles obtained become similar to the case of the inlet located at usual height of 2/3 of the diameter.

ICS solar systems with two water tanks

Integrated collector storage (ICS) systems are compact solar water heaters, simple in construction, installation and operation. They are cheaper than flat plate thermosiphonic units, but their higher thermal losses make them suitable mainly for application in locations with favourable weather conditions. Aiming to the achievement of low system height and satisfactory water temperature stratification, new types of ICS systems with two horizontal cylindrical storage tanks, properly mounted in stationary CPC reflector troughs are suggested. The non-uniform distribution of solar radiation on the two absorbing surfaces is combined with the seasonal sun elevation, resulting to effective water heating. In addition, the inverted absorber concept design can be applied to ICS systems with two storage tanks. In this paper, we present the design and performance of double tank ICS solar systems, which are based on the combination of symmetric and asymmetric CPC reflectors with water storage tanks. The analytical equations of the collector geometry of all models are calculated with respect to the radius of the cylindrical water storage tank and the reflector rim angles. Experimental results for the variation of the water temperature inside storage tanks, the mean daily efficiency and the coefficient of thermal losses during night are given for all experimental models. The tests were performed without water draining and the results show that the double tank ICS systems are efficient in water temperature rise during day and satisfactory preservation of the hot water temperature during night, with the upper storage tank being more effective in performance in most of the studied models.

04/01410 ICS solar systems with horizontal cylindrical storage tank and reflector of CPC or involute geometry: Tripanagnostopoulos, Y. and Souliotis, M. Renewable Energy, 2004, 29, (1), 13–38

04/01410 ICS solar systems with horizontal cylindrical storage tank and reflector of CPC or involute geometry: Tripanagnostopoulos, Y. and Souliotis, M. Renewable Energy, 2004, 29, (1), 13–38

Experimental study of CPC type ICS solar systems

Extensive experimental study on solar water heaters, which were developed in our laboratory, is presented. These solar devices are integrated collector storage (ICS) systems with single horizontal cylindrical storage tank properly placed in symmetric CPC type reflector trough. In this paper we study ICS solar systems, which differ in storage tank diameter and correlate their thermal performance and the ratios of the stored water volume per aperture area and also per total external surface area. Based on the results of this study and aiming to achieve improved ICS systems, we considered an effective tank diameter and we extracted by outdoor tests the performance of a number of experimental models differing in the absorbing surface, reflector and transparent cover. We calculated the mean daily efficiency and the thermal loss coefficient during night of each system combination. In addition, 24 h and four days operation diagrams of the variation of water temperature of the studied ICS systems are compared with the corresponding diagrams of two flat plate thermosiphonic units with mat black and selective absorbing surface, respectively. The experimental results show that ICS system with selective absorbing surface, high transmissivity of the transparent cover and high reflectance of its reflector surface performs efficiently enough, both during the day and night operation, approaching the thermal performance of the corresponding thermosiphonic unit of flat plate collector with selective absorber.

ICS solar systems with horizontal cylindrical storage tank and reflector of CPC or involute geometry

The use of a horizontal cylindrical water storage tank contributes to pressure resistant, low height and efficient ICS solar systems. These systems can satisfactorily achieve water heating when the cylindrical storage tank is combined with stationary CPC or involute type curved reflectors. The diameter of the cylindrical storage tank determines the length of the reflectors, the system depth and the ratio of the stored water per aperture area. In these solar systems the storage tank can be partially thermally insulated to suppress thermal losses from it to the ambience. We constructed four experimental models with truncated symmetric CPC reflectors, two with 90° and other two with 60° of acceptance angle, half of them without and half with a 1/4 thermally insulated storage tank cylindrical surface. In addition, we constructed two ICS systems with involute reflectors, with acceptance angle 180°, one without and the other one with a 1/4 thermally insulated storage tank. The six ICS systems were tested under the same weather conditions and without water drain, to determine their stored water temperature variation, mean daily efficiency and thermal losses during night. The results showed that CPC reflectors contribute to efficient operation of systems day and night, while involute reflectors mainly to the water heat preservation during night.

The Checking of Horizontal Cylindrical Steel Storage Tanks

The deformation of the cross sections of the compartments of horizontal cylindrical storage tanks, which occurs during manufacture and when they are loaded during use, is analyzed. Volumetric and geometric methods of checking storage tanks are also analyzed. Recommendations are made on choosing the function for describing the close-to-circular cylindrical shape of storage-tank compartments and on the use of volumetric and geometric methods of checking horizontal cylindrical steel storage tanks.

An experimental and numerical study of thermal stratification in a horizontal cylindrical solar storage tank

The thermal behaviour of a horizontal cylindrical storage tank has been investigated both experimentally and numerically. Four sets of experiments have been carried out where cold water is injected into the bottom of the tank with three different initial thermal fields. The first one is the tank with initial thermal stratification with bottom temperature the same as the inflow temperature. The second set is the tank with the initial thermal stratification, the bottom being at a relatively higher temperature than the inflow temperature. The third set is an initially heated isothermal tank and the fourth is the same as the first set of experiments except that the straight tube inlet nozzle is replaced by a 30° downward bent divergent conical tube. The above experiments show that better thermal stratification can be obtained using the divergent conical tube as the inlet nozzle due to the diffusion effect of the nozzle. Also a slight improvement in the tank performance has been achieved in the second set of experiments when the initial bottom temperature of the tank is higher than the injected cold water temperature. To check the accuracy of the experimental results two different types of one-dimensional numerical models, namely Turbulent Mixing Model and Displacement Mixing Model have been developed and the results are compared with the experiments. This comparison indicates that the numerical results are in good agreement with the experiments especially at the top of the tank.

Horizontal vessels on fixed supports used for storing high-temperature liquid: An experimental validation of finite element modelling

Horizontal cylindrical storage vessels are normally supported on two saddles. When used for storing high-temperature fluid, high values of thermal stress can be avoided by providing one of the supports with a sliding base. However, this ideal may be difficult to achieve in practice and vessels are sometimes found where both saddles have become rigidly fixed to the foundation. In view of this there may be certain advantages in dispensing with the concept of a sliding saddle support altogether and installing the vessels with both saddles permanently fixed to the foundation. Where this is adopted, the vessels and saddles must be designed to carry the thermal stresses that arise from the imposed restraint of the saddle base. Since this procedure is outside normal practice, as set out in the existing pressure vessel codes and standards, it is necessary to undertake detailed analytical investigations, say, using finite element analysis (FEA), to establish the behaviour of the vessels when this approach is used. In order to validate the predictions of temperature and stress obtained from the FEA used in the investigations, it was considered important to carry out some experimental work. This paper reports the techniques used and describes two experimental procedures which were performed on vessels mounted on two quite different saddle designs, both of which are widely used in industry.