8 research outputs found
Effect of heating elements types on air preheater performance: Review
No full textIn the air conditioning, steel industry, and power plants, rotating heat exchangers are utilized to preheat air for use in waste heat recovery or steam generators. In this article, various rotating heat exchangers that are utilized in thermal power plants have been presented to preheat the air supplied to the steam generators. The heat transfer between two fluid streams is accomplished in these devices via a rotating matrix that functions as a thermal accumulator by alternatingly coming into contact with the two fluid streams. Although a considerable number of studies have investigated the influence of types of heating elements on the performance of air preheaters, there is a scarcity of exhaustive review articles that encompass the latest developments in this domain. This paper provides a comprehensive review of recent available studies that investigate the impact of flow configuration, material, and geometry of the heating elements on the air preheater thermal hydraulic performance. It found that the replacement of the air preheater's baskets with new ones featuring distinct profiles increased the heat transmission rate. Also, the resistance coefficient and Nusselt number increased in tandem with the corrugation angle. The heat regeneration temperature and the heat exchanger's efficiency were observed to decrease as the matrix's rotating speed and the hot flow's mass flow rate increased, according to the results
TEMPERATURE DISTRIBUTION WITHIN THE RISING PIPE IN FLAT PLATE SOLAR COLLECTOR
No full textIn the present study, the effect of increasing absorption area by using two different cross-section shapes of rising pipe namely semi-circle cross-section (model -A-) and elliptic cross-section (model -B-) on the temperature distribution of operating liquid within rising pipe of the FPSC is studied numerically and experimentally. Experimental tests are conducted under weather Baghdad – Iraq, while the numerical results are obtained by using Ansys Fluent CFD. The difference between the experimental findings and numerical findings for the average temperature of the water in the tank and the temperature of the operating liquid at exit rising pipe is 8.12 % and 8.36 % respectively. The results have shown that the temperature distribution for all new models higher than the traditional model. Furthermore, model -B- has higher other models under study. Hence, the best model according to the current study is model -B- increase by (2.4%), (2.2%) and (2.5%) regarding the temperature of the operating liquid at the inlet, center, and outlet respectively compared to the traditional mode
PERFORMANCE ENHANCEMENT FOR ROTARY AIR PREHEATER OF A THERMAL POWER PLANT
No full textThe corrosion phenomenon is considered the main problems for air preheater in thermal power plant. The boiler flue gas contamination leads to decrease the air preheater performance and increases the maintenance cost, which causes the degradation of the cold end heating elements and thus leads to decrease the heat recovery rate. In this study, an experimental investigation was done for the transient thermal behavior and the pressure drop of the standard regenerative air preheater (Pmatrix) model, evaluating the performance factor, then modifying the air preheater (P+CG) model by changing the plates at the cold end last basket to the coarse gravel media. Since the gravel media have low thermal conductivity and predicted to give a high pressure drop, a new technique was done for the modified air preheater to compensate the low heat transfer rates and reduce the pressure drop in the gravel media by inserting bypass tubes at ratios (i and s), Which, the (i) model represents the inner aperture of tubes for the hot baskets facing to the inner aperture of tubes for the cold basket. While (s) model the insertion the tubes of the hot baskets as a staggered distribution with the tubes for the cold basket. The experimental investigation was carried out for the Reynolds number based on the test duct hydraulic diameter at a range of 24500
INVESTIGATIVE STUDY OF THERMAL PERFORMANCE OF THERMOSYPHON SOLAR COLLECTOR
No full textExperimental and Numerical investigation has been performed to improve the thermosyphon thermal performance. Optimization process concentrated on both the water and the operating liquid temperature inside the tank and the thermosyphon. For this purpose, three different models of improvement methods have been studied that depend on increasing the surface area with no changing in the volume of operating liquid. The first one (case-A-) is by add ten ring fins about the absorber pipe. The second method (Case-B-) is by add twenty ring fins about the absorber pipe. While, the third way (Case-C-) is by add ten ring fins with ten grooves about the absorber pipe. The thermosyphon thermal performance was compared between the traditional model and experimental model. Moreover, numerical simulate for all cases were done with computational fluid dynamic (CFD), ANSYS 19.R3. It was observed through the results that a good convergence between the numerical and, experimental results. Furthermore, the thermal performance for case-A- is found greater than all other cases under study
HEAT TRANSFER INSIDE BUILDING- CLADDING SOLAR COLLECTOR
No full textIn this work numerical and experimental investigation have been adopted to collect and store solar energy in exterior-wall cladding, Various improvements have been investigated inside and outside the duct to increase the efficiency of thermal heating. ANSYS software has been used to simulate current case. Results show that there is a good agreement between experimental and numerical results and this agreement increases as air velocity increases. The average percentage error for air inside duct at velocity of air 1 m/s, 3 m/s and 5 m/s is 8%, 16.5% and 5% respectively. Several vertical cooper cylinders with 12 mm diameter were added inside basin to increase the surface area. It has been found that the enhancement in temperature of air between this case and Smooth Duct, Smooth Cover base model for air velocity of 1,3and 5 m/s is 3, 4 and 11 % respectively. The effect of increasing surface area by using granular (corrugated) duct on the air temperature distribution along the duct. Have been also investigated the percentage enhancement in temperature of air between this case and previous base smooth duct case for velocities of 1, 3 and 5 m/s is 19.4, 28.6 and 16.5 % respectively. The enhancement in heat transfer when using both granular hollow sphere duct with vertical metal cylinders for air velocity of 1, 3 and 5 m/s is 27.5, 33 and 35.2 % respectively
