Green tides dominated by Ulva prolifera have be present in the Southern Yellow Sea for 15 consecutive years. They not only damage the marine environment, but also cause economic losses to coastal cities. However, there is still no fully effective approach for preventing green tides. In this article, approaches for the prevention of U. prolifera taken over recent years are reviewed. They can be generally divided into physical, chemical, and biological approaches. Physical approaches have been used to control the overwhelming green macroalgae bloom and inhibit the germination of U. prolifera, including physical salvage approach, refrigeration net technology, improved farming methods and raft technology, and modified clay method. These approaches require significant labor and material resources. Many chemical reagents have been used to eliminate U. prolifera early germination and growth, such as oxidative algaecide, acid treatment, heavy metal compounds, antifouling coating, and alkaloids. Chemical approaches have high efficiency, high economic benefit, and simple operation. Presently, biological control approaches remain in the exploratory stage. The verification of pilot and large-scale experiment results in sea areas is lacking, including the application of large organisms and microorganisms to control U. prolifera, and some of the mechanisms have not been thoroughly studied. This article introduces the three types of approaches, and evaluates the advantages and disadvantages of different methods to facilitate the reduction of the green tide bloom scale in the Southern Yellow Sea.

Globally, vaccination plays a vital role in controlling the Covid-19 pandemic. However, the cold supply chain is essential for vaccine storage and logistics services. In a country like India, the last-mile logistics of vaccines is a challenging task. The cold chain is indispensable for the Covid-19 vaccine drive to the rural areas. The demand for cold storage increases rapidly due to the rapid Covid-19 vaccine drive. The conventional cold storage facility has a more significant threat to the grid power quality and environmental impacts. The energy demand and greenhouse gas emission of traditional cold storage lead to global warming. The micro cold storage facility has to be developed rapidly to accelerate the vaccine drive to the last mile of the county with reliable and affordable energy sources. In addition, climate change mitigation is ensured by the renewable energy utilization in the Covid-19 vaccine drive. The proposed novel micro cold storage aims to be silent, clean, mobile, without moving parts, and reliable for the last-mile vaccine logistics as a vaccine carrier to the remote rural areas. This paper deals with the novel design, development, and experimental investigation of solar photovoltaic powered thermoelectric-based micro cold storage as a Covid-19 vaccine carrier for rural areas. The design consideration of Covid-19 vaccine storage has been reported. The experimental results ensure the World Health Organization recommended vaccine storage (i.e., vaccine carrier) temperature range of +2 to +8 °C. Therefore, green energy and refrigeration system provide environmental sustainability by mitigating 700kg of annual carbon emission.

This paper presents the environment-friendly mixture compositions of hydrocarbons (HC)– and hydrofluorocarbon (HFC)–based ternary mixtures that can be better alternatives for R134a in domestic refrigeration units. Combustible refrigerant HCs (R290, R600, R600a) and HFCs (R152a and R161) are used along with the dilutants R13I1, R245fa, R134a, R227ea, and R125 and their flammability studies were carried out theoretically. Minimum inerting concentration (MIC) is used to classify the flammable and non-flammable zones of the ternary mixtures. MIC points estimated with modified thermal balance method (MTBM) are compared with 62 experimental data points available in the literature. It was calculated that MTBM predicted the MIC values with in ±9%, for most of the working fluids selected in this study. R13I1 is used along with all the refrigerant (HC and HFC) combinations (as the first dilutant) while the effect of other dilutants on the system performance is carried out theoretically. It is predicted from the flammability diagram (developed in this study) that the inert effect of R227ea is higher than of R245fa, R134a, and R125. It is also observed that the drop in coefficient of performance (COP) is significant with R290/R13I1/R245fa (with increase in R245fa) mixture when compared to other combinations. Finally, mixtures R600a/R13I1/R245fa, R600a/R13I1/R227ea, R600a/R13I1/R134a, R600a/R13I1/R125, R161/R13I1/R134a, R290/R13I1/R125, R161/R13I1/R227ea, and R161/R13I1/R125 are identified as the best environment-friendly mixture compositions as alternatives to R134a. It is also calculated that the mixture R600a/R13I1/R125 possesses COP greater than 10% to R134a at the same working conditions.

The work aims to analyse an ejector refrigeration system powered with solar energy through serially connected collectors to lower greenhouse gases. The collectors chosen for the work are Scheffler and parabolic collectors with an area of 2.5 m² and 6 m², respectively. The steam generated by the collectors is stored temporarily in a 15-l storage tank. The thermic fluid transfers heat between the steam storage tank and refrigerant, and thus the generator temperature increases. This design was intended as an alternate for a traditional 3.5 kW room air conditioner with substantially lower energy consumption. This modified system consumed lesser energy input of about 20–30% than conventional air conditioners. Further, for the same specification, the ejector system has consumed less power of about 2.475 kW than the traditional refrigeration system.

This experimental study analyzed the use of solar photovoltaic energy for operating a novel twin-circuit DC milk chiller without batteries using water-based cold thermal energy storage for different seasons in Chennai, India. HFC-134a and HC-600a were used as refrigerants in the two individual circuits. For each season, the test was conducted continuously for 18 days to analyze the quantity of generated ice that could be utilized to chill 10 L of milk in the morning and in the evening. The average quantity of ice formed per day in the ice bank during monsoon, winter, and summer seasons was found to be 3.61, 19.75, and 27.97 kg, respectively. Thus, it is evident that the use of solar energy with thermal energy storage is effective for operating the milk chilling unit for two seasons, namely winter and summer. However, the system requires an additional power source for continuous operation during the monsoon season. It is noteworthy to mention that the use of a solar milk chiller instead of a conventional milk chiller resulted in 91.15% lesser CO₂ emission with 27.6% less LCC. In this study, solar photovoltaic power was observed to be a good choice for chilling milk in the context of global warming and energy consumption. The use of thermal energy storage also allows the initial cost to be reduced.

The objective of the work is to analyse and to improve the efficiency of solar-powered ejector refrigeration system integrated with flat-plate collector and Scheffler concentrator. The Scheffler concentrator of 2.7 m² and flat-plate collector of 5 m² collecting area are coupled with the storage tank of 15 l capacity. The developed system was designed for a potential replacement of conventional 1-ton room air conditioner with much reduced electrical energy consumption. The system was built based on two key subsystems namely ‘Scheffler concentrator-based vapour system’ and ‘ejector-based cooling system’. The pilot effort showed promising results with the probability of energy-saving potential as near 70 to 80% over conventional air conditioners.

The issues of food safety and environmental protection are attracting more and more attention. Everyday, a large number of cold chain products are delivered from suppliers to customers. The cold chain products require refrigeration equipment in delivery and should be delivered to customers as soon as possible. Therefore, the challenge of reducing carbon emission and improving the customer satisfaction should be solved. This study presents the impact of carbon emission, customer satisfaction, construction cost, and operation cost on the location of cold chain logistics distribution center. A multi-objective location model for cold chain logistics distribution center considering carbon emission is established. The carbon emission equivalent cost model considers the dynamic carbon emission during transportation and the static carbon emission of the distribution center. The penalty cost under the time window is introduced into the penalty cost model of customer satisfaction, which represents a multi-objective mixed-integer linear programming problem. A non-dominated sorting genetic algorithm II (NSGA-II) is used to design the program through double-layer composite coding. NSGA-II uses a fast non-dominated sorting approach to reduce the computational complexity of non-dominated sorting. This algorithm uses the elitist control strategy, which does not need to share parameters and is more efficient in the multi-objective optimization process. The numerical results show that the proposed algorithm can generate appropriate Pareto solutions for all objectives.

One of the important ways to the efficiently use of low-grade thermal energy is the adsorption refrigeration technology. However, it has some drawbacks such as low specific cooling power and coefficient of performance, especially under using the conventional adsorption pairs. Therefore, new adsorption pairs are tested in solar adsorption ice-maker and compared with other conventional pairs data from open literature to find the tendency of improving the solar adsorption ice-maker performance. The experimental test rig has been built in Upper Egypt in Qena City. Four different new adsorption pairs of granular activated carbon/R-410A, granular activated carbon/R-511A, Maxsorb III/R-410A, and Maxsorb III/R-511A are used. It is demonstrated that Maxsorb III/R-511A pair based solar adsorption ice-maker produced the highest values for specific cooling power, coefficient of performance, and ice production per 1 kg of adsorbent of approximately 226.7 W/kgₐdₛ, 0.197, and 1.96 kg/kgₐdₛ, respectively. While granular activated carbon/R-410A based solar adsorption ice-maker produced the lowest values of ice production per 1 kg of adsorbent and coefficient of performance of 1.38 kg/kgₐdₛ and 0.104, respectively. Moreover, it can be concluded that the tested pairs are feasible to be used in solar adsorption ice-maker systems, especially in such hot climate of Upper Egypt for food and vaccine preservation and storage.

In recent times, solar energy has been utilized for refrigeration systems due to its efficiency and clean form of energy. Moreover, the evacuated tube collector (ETC)–assisted vapor absorption refrigeration system plays a significant role in the modern industrial world compared to the traditional electrical system. However, the conventional vapor absorption refrigeration system design is complex in nature and causes corrosion in the system. Therefore, in this research, novel Generalized Approximate Reasoning–Based Intelligent Control (GARIC) and Hybrid Ant Colony African Buffalo Optimization (HACABO) methods based on an ETC-linked 5-kW vapor absorption refrigeration system are proposed depending on lithium bromide-water (LiBr-H₂O). Primarily, the Haryana region’s solar radiation and weather parameters were taken over a year to simulate the ETC system. ETC collects the solar energy for the refrigeration cycle, and the efficiency of the ETC is estimated using the GARIC method as per the input of solar radiation, collector area, and used solar energy. Moreover, the efficiency of the ETC is optimized using the proposed HACABO method. The modified polynomial fits curved equation is utilized for performance analysis. The simulation model of the solar cooling absorption system is carried out in the MATLAB platform. The coefficient of performance (COP) rate of the absorption cycle has gained 0.82% with the help of HACABO. Compared to other recent associated models, the proposed model has maximized the COP in the finest range.

Bioreduction of selenium oxyanions to elemental selenium is ubiquitous; elucidating the properties of this biogenic elemental selenium (BioSe) is thus important to understand its environmental fate. In this study, the magnetic properties of biogenic elemental selenium nanospheres (BioSe-Nanospheres) and nanorods (BioSe-Nanorods) obtained via the reduction of selenium(IV) using anaerobic granular sludge taken from an upflow anaerobic sludge blanket (UASB) reactor treating paper and pulp wastewater were investigated. The study indicated that the BioSe nanomaterials have a strong paramagnetic contribution with some ferromagnetic component due to the incorporation of Fe(III) (high-spin and low-spin species) as indicated by electron paramagnetic resonance (EPR). The paramagnetism did not saturate up to 50,000 Oe at 5 K, and the hysteresis curve showed the coercivity of 100 Oe and magnetic moment saturation around 10 emu. X-ray photoelectron spectroscopy (XPS) and EPR evidenced the presence of Fe(III) in the nanomaterial. Signals for Fe(II) were observed neither in EPR nor in XPS ruling out its presence in the BioSe nanoparticles. Fe(III) being abundantly present in the sludge likely got entrapped in the extracellular polymeric substances (EPS) coating the biogenic nanomaterials. The presence of Fe(III) in BioSe nanomaterial increases the mobility of Fe(III) and may have an effect on phytoplankton growth in the environment. Furthermore, as supported by the literature, there is a potential to exploit the magnetic properties of BioSe nanomaterials in drug delivery systems as well as in space refrigeration.