Performance analysis and optimization biogas-fuelled cogeneration systems in sewage treatment plants

In terms of securing energy resources and reducing environmental problems, the utilization of biomass has been studied. Biomass is known as renewable energy which can supply more stable energy than other renewable energy types such as wind and solar energy. Thus, its application has become more important in the recent years. Abundant biogas has been produced by anaerobic digestion of sewage sludge, one of waste type biomass in sewage treatment plants. Thus, its utilization potential is very high. The installation of efficeint power plant systems in sewage treatment plants is indispensable for the efficient utilization of biogas. In this study, micro gas turbines (MGTs) were used as the prime movers of Cogeneration Systems (CGS5). MGTs have low emissions and maintenance requirements and can also use fuel with low heating value. The performance and the optimized configuration method of the system was investigated in this study.In the initial stage, the effect of ambient temperature on the basic component of the biogas-fuelled CGS, the energy balance of the anaerobic digestion and performance of the MGT-CGS was clarified. On the basis of this result, improvement of the performance of the biogas-fuelled CGS in a cold region that has high and varies heat demand throughout the year was investigated. In this case, the CGS alone cannot cover the total heat demand and hence other auxiliary equipment including a boiler, a heat pump and a gas storage system were also considered. It was found that performance can be improved when the boiler was replaced by the heat pump, and all biogas produced and exhaust heat recovered by the CGS can be efficiently used when the gas storage system was also installed with the CGS. In the second stage, focused was given to the optimized configuration method of the CGS that can utilize all biogas produced efficiently regardless of the region and ambient temperature conditions. It was clarified that in terms of energy utilization efficiency, the most efficient CGS can be obtained when the exhaust heat index of the CGS, exhaust heat recovery efficiency , e/1r is approximately equal to the energy index of the plant, ratio of annual average of heat demand Qhto the biogas energy produced Qb.p, (Qh.d I Qb.p)On the other hand, MGTs are classified as gas turbines that have electrical power output capacity of 30-300kW, and depending on the output capacity, their electrical power output efficiency at full load and partial load are different. Thus, in the third stage, the suitable size (electrical power output capacity) of an MGT-CGS depending on the scale of the sewage treatment plant (biogas energy produced) and its optimization was investigated. It was found that the most efficient MGT-CGS can be obtained when the fuel energy input of the MGT-CGS at full load is approximately equal to the biogas energy produced of the plant. Finally, it can be summarized that this study successfully clarifies in detail the most efficient configuration of cogeneratiofls based biogas-fuelled power plants and, this study can also give valuable guide regarding the method of the performance optimization of a biogas-fuelled CGS

PV cools: Close loop water cooling system for PV module

Significant drop in performance due to extreme rise in solar cells temperature. Dust deposition on the module surface inhibits the incoming solar irradiation from reaching the solar cell

Review on recent development micro gas turbine -trigeneration system and photovoltaic based hybrid energy system

Research on distributed power generation as an alternative method to the conventional power generation system continue to be developed to improve its commercialization capabilities. The cogeneration system and trigeneration system are technological improved alternatives in distributed generation where they offer enhancement and reliability in term of efficiency, emission performances and economic benefits. However, it is more feasible to implement the trigeneration system for most commercial and domestic distributed generations as the cooling demand is deliberately high compared to heating demand especially in hot and humid climate locations. Moreover, micro gas turbine is observed to be a beneficial prime mover in cogeneration and trigeneration system based on several criteria such as ability on acquiring high heat to power ratio characteristic as well as lower greenhouse gas emission. On the other hand, the role photovoltaic in building integrated system provides opportunities for renewable energy system engagement in trigeneration based distributed generation systems. This paper emphasize on summarizing the research work perform on cogeneration system or trigeneration system in hybrid mode with photovoltaic. There are also preceding sections on overviewing the state of art of cogeneration system and the trigeneration system as well as photovoltaic technologies in power generation

A performance and technoeconomic study of different geometrical designs of compact single-pass cross-matrix solar air collector with square-tube absorbers

This manuscript presents a performance study on a forced convection single-pass solar air heater channel with compact cross-matrix absorber (CMA) incorporating metal hollow square-tube absorbers. Four different geometries of CMA (Type I, II, III and IV) were investigated experimentally to evaluate their efficiency, pressure drops and heat transfer parameters. The experiments were conducted with uniform heat flux (indoor) and outdoor solar radiation as heat source. The air mass flow rates used were between 0.0142 kg/s and 0.0360 kg/s. Techno-economic feasibility studies were conducted using cost-benefit ratio (AC/AEG) method. Thermal efficiency of the CMA obtained by Type I with 76%, being the highest. CMA Type I also exhibited the highest temperature elevation than other configurations with 15.3 °C and thermal capacity of 38.7 kJ. Maximum pressure drop obtained was 1.33 Pa in turbulent condition with Reynolds number of 50,794. Type I has the advantage of high performance CMA and has comparatively lower cost-benefit ratio (AC/AEG) of 0.15 RM/kWh than other type of thermal absorbers. © 2018 Elsevier Lt

Experimental analysis on the effect of cooling surface area and flow rate for water cooled photovoltaic module

Application of water spray or water flow on the surface of photovoltaic (PV) modules is one of the techniques used to increase efficiency. Main parameter that affect the performance by this technique is water flow rate and cooling surface are. However, there is less study focus on those parameters. Thus, the objective of this paper is to investigate the effect of water-cooled surface area and water flow rate on the temperature and power output of the PV. Orifices were used to create half-cooled and fully-cooled surface area for water to flow as cooling techniques while the hand valve was used to control the flow rate of water at 120 L/h, 180 L/h and 240 L/h flowing onto the panel. A solar simulator was constructed and used to provide 600 W/m2, 1,000 W/m2, and 1,200 W/m2 irradiance for the panel. The testing methodology consists of three different experiments for each irradiance level. It was found that more cooling surface area covered could significantly reduce temperature in any irradiance level, and fully-cooled module could keep the temperature at below 40 °C eventhough the irradiance was at 1,200 W/m2. In addition, the optimum flow rate also depends on the cooling surface area. Thus, there is a unique relation between cooling surface area and optimum flow rate. Thus, further investigation is needed on this relation

Mathematical Modelling of Stingless Bee Honey Dewatering using Low-Temperature Vacuum Drying with Induced Nucleation Bubbling

ow-temperature vacuum drying with induced nucleation boiling (LTVD-NB) was developed to dewater heat-sensitive materials such as stingless bee honey (SBH). However, its performance can be further optimised to achieve an efficient LTVD-NB operation. The objective of this paper is to investigate the most fitting drying model for dewatering SBH and to develop a suitable mathematical drying model that can be used to predict and optimise dewatering SBH using LTVD-NB. Established experimental data was used to develop the mathematical model. The data result showed that the logarithmic model had the best fit for drying SBH using LTVD-NB as compared to other models based on the highest value of R 2 and the lowest Root mean square, RMSE and reduced chi-square, χ 2 values which are 0.999988, 7.87E-05, and 1.41E-08, respectively. The model was further regressed to obtain an optimised mathematical model to better predict an LTVD-NB operation to dewater SBH. In conclusion, an optimised drying model to describe the dewatering process of SBH using the LTVD-NB method was able to be developed based on the multiple regression analysis of the obtained experimental data. Therefore, the drying model can predict the efficiency of this process just by giving the temperature and surface roughness values as input information

Mathematical modelling of stingless bee honey dewatering using lowtemperature vacuum drying with induced nucleation bubbling

Low-temperature vacuum drying with induced nucleation boiling (LTVD-NB) was developed to dewater heat-sensitive materials such as stingless bee honey (SBH). However, its performance can be further optimised to achieve an efficient LTVD-NB operation. The objective of this paper is to investigate the most fitting drying model for dewatering SBH and to develop a suitable mathematical drying model that can be used to predict and optimise dewatering SBH using LTVD-NB. Established experimental data was used to develop the mathematical model. The data result showed that the logarithmic model had the best fit for drying SBH using LTVD-NB as compared to other models based on the highest value of R 2 and the lowest Root mean square, RMSE and reduced chi-square, χ 2 values which are 0.999988, 7.87E-05, and 1.41E-08, respectively. The model was further regressed to obtain an optimised mathematical model to better predict an LTVD-NB operation to dewater SBH. In conclusion, an optimised drying model to describe the dewatering process of SBH using the LTVD-NB method was able to be developed based on the multiple regression analysis of the obtained experimental data. Therefore, the drying model can predict the efficiency of this process just by giving the temperature and surface roughness values as input information

Effect of surface roughness and temperature on the performance of low-temperature vacuum drying with induced nucleation boiling method in dewatering stingless bees honey

The Low-Temperature Vacuum Drying with Induced Nucleation Boiling (LTVD-NB) was developed to dewater honey. However, the effects of surface roughness (SR) and temperature of the LTVD-NB for honey are still unknown. Thus, the objective of this study is to investigate the effect of SR and temperature on dewatering rate and heat transfer performance. The honey sample was heated at 40-50 °C using heater pipes with SR 0.80-11.33 µm at a 5 kPa. It was found that the dewatering rate obtained at the highest SR and temperature was five times higher than the lowest SR and temperature. By increasing the SR from 0.80 to 11.33 µm, the Heat Transfer Coefficient (HTC) increased by 143% as more nucleation sites were present on the surface. Besides, when temperature increased heat flux, bubble frequency and HTC also increased. In conclusion, the dewatering rate increases when SR and temperature increase, which is correlated with nucleation sites and bubble frequency

Multi-angle swirling fluidized bed drying of stingless bees pot-pollen

Pot-pollen is another stingless bee product, a mixture of pollen, honey, and bee enzyme stored in cerumen pots. Pot-pollen is protein rich and have therapeutic properties. However, they contain high moisture rendering them susceptible to microbial and fungi growth which will lead to spoilage without proper storage. Conventional methods to remove moisture includes sun drying, oven drying, and food dehydrators. However, they can be unhygienic, reduce pot-pollen quality, and lengthy drying time. Swirling fluidized bed dryer (SFBD) is a promising alternative as they have rapid drying time without damaging the nutrients. The addition of multi-angle swirling distributor (MASD) has the potential to improve drying performance without additional energy input. The current study aim to investigate the drying performance of swirling fluidized bed dryer with multi-angle distributor. Raw pot-pollen is dried in a lab scale SFBD at 3.0 m/s using single angle and multi-angle swirling distributors, 6767, 6730, and 6745. The results shown that the multi-angle swirling distributors 6730 and 6745 improved the drying performance of SFBD, by 17.1 % and 6.5 %, respectively. The best drying performance is shown by the 6730 distributor. Thus, multi-angle SFBD is able to rapidly dry the heat-sensitive stingless bee pot-pollen and represented significant improvement from single angle SFBD

Sustainable Carrageenan/Nanocomposite Films Incorporated with Optimized Zingiber officinale Extracts for Active Packaging Systems

Optimized Bentong ginger (BG) extract using ultrasonic-assisted extraction (UAE) was incorporated in hybrid carrageenan/nanocomposite biopolymers for active packaging films. The design of experiments based on central composite design was applied for the study of the operating parameters (amplitude, sonication time, and solvent concentration) of UAE in the recovery of phenolic compounds from BG. Optimized extracts were analyzed for the content of 6-gingerols in liquid chromatography quadrupole time-of-flight mass spectrometry and formulated in carrageenan/nanocellulose hybrid films for active packaging applications. The mechanical properties of the films and release behavior of antioxidant compounds into food simulants were investigated. The optimized UAE BG extract was found efficacious as an antioxidant agent in active packaging