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Abstract The practical implementation of aqueous Zn‐ion batteries (ZIBs) for large‐scale energy storage is impeded by the challenges of water‐induced parasitic reactions and uncontrolled dendrite growth. Herein, we propose a strategy to regulate both anions and cations of electrolyte solvation structures to address above challenges, by introducing an electrolyte additive of 3‐hydroxy‐4‐(trimethylammonio)butyrate (HTMAB) into ZnSO4 electrolyte. Consequently, the deposition of Zn is significantly improved leading to a highly reversible Zn anode with paralleled texture. The Zn/Zn cells with ZnSO4/HTMAB exhibit outstanding cycling performance, showcasing a lifespan exceeding 7500 h and an exceptionally high accumulative capacity of 16.47 Ah cm−2. Zn/NaV3O8·1.5H2O full cell displays a specific capacity of ~130 mAh g−1 at 5 A g−1 maintaining a capacity retention of 93% after 2000 cycles. This work highlights the regulation on both cations and anions of electrolyte solvation structures in optimizing interfacial stability during Zn plating/stripping for high performance ZIBs.

Abstract Dehumidification is one of the key challenges facing the air conditioning (AC) industry in the treatment of moist air. Over many decades, the dual role of heat exchangers of AC chillers for the sensible and latent cooling of space has hindered the thermal-lift reduction in the refrigeration cycle due to the requirements of water vapor removal at dew-point and heat rejection to the ambient air. These practical constraints of AC chillers have resulted in the leveling of energy efficiency of mechanical vapor compressors (MVC) for many decades. One promising approach to energy efficiency improvement is the decoupling of dehumidification from sensible processes so that innovative but separate processes can be applied. In this paper, an advanced microwave dehumidification method is investigated in the laboratory, where the microwave (2.45 GHz) energy can be irradiated onto the dipole structure of water vapor molecules, desorbing rapidly from the pores of adsorbent. Results show a significant improvement in performance for microwave dehumidification, up to fourfold, as compared to data available in the literature.

The hybrid indirect evaporative cooling-mechanical vapor compression (IEC-MVC) process is an emerging cooling technology that combines the advantages of IEC and MVC, i.e., effective temperature and humidity control, high energy efficiency, and low water consumption. This paper presents an experimental study of the hybrid IEC-MVC process. A 1-Rton pilot is fabricated by connecting IEC and MVC in series, and its performance is evaluated under different operating conditions (outdoor air temperature and humidity, air flowrate, compressor frequency). Results revealed that the outdoor air temperature and humidity could be lowered to 5–15 °C and 5–10 g/kg, respectively. The IEC handles 35%–50% of the total cooling load, and the energy consumption can be reduced by 15%–35% as compared to standalone MVC. Moreover, the condensate collected from the evaporator can compensate for >70% of water consumption in IEC, making the system applicable in arid regions. Based on the derived results, a simplified empirical model is developed for rapid evaluation of the IEC-MVC process, and the energy-saving potential in major cities of Saudi Arabia is estimated.

The canned food market is growing at an annually average rate of 3.6% due to easy access and awareness of dietary requirements, leading to a surge in water withdrawal and an estimated supply-demand gap of 40% by 2030. The conventional desalination processes are not sustainable due to high energy requirements and chemicals injection. The adsorption cycle is an emerging technology for desalination due to its temperature operation. It has many advantages over conventional desalination processes including integration synergy to improve overall performance. The conventional AD cycle processes, however, have lower performance due to inefficient packing of adsorbent in the beds and heat transfer losses to their massive heat exchangers. In this article, we propose an innovative pressure driven adsorption (PDAD) cycle to overcome conventional AD cycle limitations. In PDAD, firstly, low pressure steam is used to regenerate the adsorbent which eliminates the huge infrastructure requirement of water circulation and secondly, steam selectively extracts water vapours from pores, reducing energy consumption. We have tested the PDAD pilot and showed successful regeneration of silica gel at motive steam pressure of 2–5 bar. We also demonstrate that discharge steam from the PDAD at 65 °C can be used as a heat source for a multi effect desalination system when operating in hybrid mode to overcome its operational limitations. Our experiments show that the MED + PDAD cycle increases water production by up to 22% as compared to an earlier hybrid MEDAD cycle. The proposed system has excellent thermodynamic synergy with the combined CCGT power and desalination plant, where low-pressure bleed steam can be utilized more efficiently.

In Saudi Arabia, air conditioning is the main consumer of electricity, and increasing its energy efficiency is of great importance for energy conservation and carbon footprint reduction. This study presents the evaluation of a hybrid indirect evaporative cooling-mechanical vapor compression (IEC-MVC) cycle for cooling applications in Saudi Arabia. Most cities in this country are characterized by a high sensible cooling demand, and a few cities near the coasts of the Red sea and the Persian Gulf also need dehumidification. By employing the hybrid system, IEC can undertake about 60% of the cooling load in the summer of arid cities, and energy consumption can be reduced by up to 50%. The contribution of IEC and energy saving are less significant in humid cities because the latent loads have to be handled by MVC. Over the whole year, IEC contributes 50% of the total cooling capacity and reduces energy consumption by 40% in dry cities, while the saving is lower at 15%–25% in humid cities like Mecca and Jeddah. The average water consumption of the IEC is in the range of 4–12 L/hr. The water consumption can be replenished by the condensate collected from the MVC evaporator if the ambient humidity is high. Based on the annual performance, the cost of the IEC-MVC process is calculated, and it is 15%–35% lower than the standalone MVC. The results demonstrate the great potential of the hybrid IEC-MVC cycle in Saudi Arabia.

Since the 1970s, commercial-scale thermally-driven seawater desalination plants have been powered by low-grade energy sources, drawn either with low-pressure bled-steam from steam turbines or the solar renewable energy harvested that are supplied at relatively low temperatures. Despite the increasing trend of seawater reverse osmosis plants, the role of thermal desalination methods (such as multi-stage flashing and multi-effect distillation) in GCC countries is still relevant in the Arabian Gulf, arising from higher salinity, the frequent algae blooms of seawater and their ability to utilize low temperature heat sources. Given the urgent need for lowering both the capital and operating costs of all processes within the desalination industry and better thermodynamic adaptation of low-grade heat input from renewable sources, the present paper addresses the abovementioned issues by investigating the direct contact spray evaporation and condensation (DCSEC) method. A DCSEC system comprises only hollow chambers (devoid of membranes or tubes, minimal use of chemical and maintenance) where vapor generation (flashing) utilizes the enthalpy difference between the sprayed feed seawater and the saturated vapor enthalpy of the vessels. Concomitantly, vapor is condensed with spray droplets of cooler water (potable) in adjacent condenser vessels, employing a simple design concept. We present detailed design and real seawater experiments data of a DCSEC system for the first time. The water production cost is calculated as $0.52/m3, which is one of the lowest figures reported compared to commercial processes presented by Global Water Intelligence.

Cooling has a significant share in energy consumption, especially in hot tropical regions. The conventional mechanical vapor compression (MVC) cycle, widely used for air-conditioning needs, has high energy consumption as air is cooled down to a dew point to remove the moisture. Decoupling the latent cooling load through dehumidification from the sensible cooling load can significantly improve the energy requirement for air-conditioning applications. Solid desiccants have shown safe and reliable operation against liquid desiccants, and several configurations of solid desiccants dehumidifiers are studied to improve their performance. However, the characteristics of solid desiccants are critical for the performance and overall operation of the dehumidifier. The properties of every desiccant depend upon its porous adsorbing surface characteristics. Hence, it has an optimum performance for certain humid conditions. Therefore, for a better dehumidification performance in a specific tropical region, the solid desiccant must have the best performance, according to the humidity range of that region. In this article, a theoretical methodology has been discussed to help the industry and chemists to understand the porous structural properties of adsorbent surfaces needed to tune the material performance for a particular humidity value before material synthesis.

Abstract In seawater desalination, the energy efficiency of practical processes is expressed in kWh_electricity or low-grade-heat per m3 of water produced, omitting the embedded energy quality underlying their generation processes. To avoid thermodynamic misconceptions, it is important to recognize both quality and quantity of energy consumed. An unmerited quantitative apportionment can result in inferior deployment of desalination methods. This article clarifies misapprehensions regarding seeming parity between electricity and thermal sources that are sequentially cogenerated in power plants. These processes are represented by heat engines to yield the respective maximum (Carnot) work potentials. Equivalent work from these engines are normalized individually to give a corresponding standard primary energy (Q SPE), defined via a common energy platform between the adiabatic flame temperature of fuel and the surroundings. Using the Q SPE platform, the energy efficiency of 60 desalination plants of assorted types, available from literature, are compared retrospectively and with respect to Thermodynamic Limit.

Life is dependent on water. However, in terms of the potential effects, water scarcity is quickly emerging as one of the most critical problems in the world. To access more fresh water for drinking, sanitation, and irrigation, water can be harvested from different forms of water on earth. Atmospheric harvesting is the best alternative for producing fresh water for everyday life and reducing global water shortages. To date, many modern technologies have been introduced for this application, with several prototypes being demonstrated. Thus, this study explores the potential benefits of the current atmospheric water harvesting systems in terms of their modes, atmospheric conditions, and production rate and examines the key factors that affect the efficiency of atmospheric water harvesting, such as temperature and humidity. According to the studies, there has been a significant advancement in energy harvesting and conversion technology, along with atmospheric water harvesting, over the past few years, including new mechanisms and technical paths. However, there are still many obstacles; in particular, most of the technologies depend on outdoor conditions. In order to overcome this issue, new directions need to be investigated. Here, we discuss the principles, advantages, limitations, and potential applications of these technologies.

Energy recovery in conventional thermal systems like power plants, refrigeration systems, and air conditioning systems has enhanced their thermodynamic and economic performance. In this regard, compact heat exchangers are the most employed for gas to gas energy recovery because of their better thermal performance. This paper presents an economic optimization of a crossflow plate-fin heat exchanger with offset strip fins. A detailed software-based numerical code for thermal, hydraulic, economic, and exergy analysis is developed for three fin geometries. Genetic Algorithm, parametric, and normalized sensitivity analyses are used to discover the most influential parameters to optimize the total cost. The parametric study showed that with the increase of mass flow rates and plate spacing, outlet stream cost and operating cost increased due to the rise in pressure drops. Finally, the optimization reduced the operational cost by ∼78.5%, stream cost by ∼64.5%, and total cost by ∼76.8%.

Agriculture and agro-based industries consume more energy, mainly derived from fossil fuels [...]

The hybrid indirect evaporative cooling-mechanical vapor compression (IEC-MVC) process is deemed a promising cooling system for hot and humid areas. It possesses the merits of high energy efficiency and strong capability of temperature and humidity control. Herein, we provide an overview of the state-of-the-art investigations over different aspects of the hybrid IEC-MVC process. Firstly, we evaluate the potential of IEC as a pre-cooler and heat-recovery device. Then, we compare the energy efficiency of IEC-MVC with standalone MVC and summarize its long-term energy-saving potential under specific weather conditions. Subsequently, we discuss the economic viability and water consumption of the hybrid process. These studies form a solid foundation for the future installation of the IEC-MVC system.

Understanding adsorption phenomena is essential to optimize and customize the energy transformation in numerous industrial and environmental processes. The complex and heterogeneous structure of the adsorbent surface and the distinct interaction of adsorbent-adsorbate pairs are attributed to the diverse response of adsorption phenomena, measured by the state diagrams of adsorption uptake known as adsorption isotherms. To understand various forms of adsorption isotherms, the surface characteristics of the adsorbent surface with the heterogeneity of adsorption energy sites must be analyzed so that they can be modified for the tailored response of the material. Conventionally, such material synthesis is based on chemical recipes or post-treatment. However, if the adsorbent's surface characteristics and heterogeneity are known, then a directed change in the material structure can be planned for the desired results in the adsorption processes. In this paper, a theoretical and mathematical methodology is discussed to analyze the structure of various adsorbents in terms of the distribution of their adsorption energy sites. The change in their surface is then analyzed, which results in the tailored or customized response of the material.

The present study provides insights into the energy-saving potential of a membrane energy recovery ventilator (ERV) for the management of building air-conditioning loads. This study explores direct (DEC), Maisotsenko cycle (MEC) evaporative cooling, and vapor compression (VAC) systems with ERV. Therefore, this study aims to explore possible air-conditioning options in terms of temperature, relative humidity, human thermal comfort, wet bulb effectiveness, energy saving potential, and CO2 emissions. Eight different combinations of the above-mentioned systems are proposed in this study i.e., DEC, MEC, VAC, MEC-VAC, and their possible combinations with and without ERVs. A building was modeled in DesignBuilder and simulated in EnergyPlus. The MEC-VAC system with ERV achieved the highest temperature gradient, wet bulb effectiveness, energy-saving potential, optimum relative humidity, and relatively lower CO2 emissions i.e., 19.7 °C, 2.2, 49%, 48%, and 499.2 kgCO2/kWh, respectively. Thus, this study concludes the hybrid MEC-VAC system with ERV the optimum system for the management of building air-conditioning loads.

This paper describes an ejector model for the prediction of on-design performance under available conditions. This is a direct method of calculating the optimal ejector performance (entrainment ratio or ER) without the need for iterative methods, which have been conventionally used. The values of three ejector efficiencies used to account for losses in the ejector are calculated by using a systematic approach (by employing CFD analysis) rather than the hit and trial method. Both experimental and analytical data from literature are used to validate the presented analytical model with good agreement for on-design performance. R245fa working fluid has been used for low-grade heat applications, and Engineering Equation Solver (EES) has been employed for simulating the proposed model. The presented model is suitable for integration with any thermal system model and its optimization because of its direct, non-iterative methodology. This model is a non-dimensional model and therefore requires no geometrical dimensions to be able to calculate ejector performance. The model has been validated against various experimental results, and the model is employed to generate the ejector performance curves for R245fa working fluid. In addition, system simulation results of the ejector refrigeration system (ERS) and combined cooling and power (CCP) system have been produced by using the proposed analytical model.

Pakistan is among the countries that have already crossed the water scarcity line, and the situation is worsened due to the recent pandemic. This is because the major budget of the country is shifted to primary healthcare activities from other development projects that included water treatment and transportation infrastructure. Consequently, water-borne diseases have increased drastically in the past few months. Therefore, there is a dire need to address this issue on a priority basis to ameliorate the worsening situation. One possible solution is to shift the focus/load from mega-projects that require a plethora of resources, money, and time to small domestic-scale systems for water treatment. For this purpose, domestic-scale solar stills are designed, fabricated, and tested in one of the harshest climatic condition areas of Pakistan, Rahim Yar Khan. A comprehensive overview of the regional climatology, including wind speed, solar potential, and ambient temperature is presented for the whole year. The analysis shows that the proposed system can adequately resolve the drinking water problems of deprived areas of Pakistan. The average water productivity of 1.5 L/d/m2 is achieved with a total investment of PKR 3000 (

For future sustainable seawater desalination, the importance of achieving better energy efficiency of the existing 19,500 commercial-scale desalination plants cannot be over emphasized. The major concern of the desalination industry is the inadequate approach to energy efficiency evaluation of diverse seawater desalination processes by omitting the grade of energy supplied. These conventional approaches would suffice if the efficacy comparison were to be conducted for the same energy input processes. The misconception of considering all derived energies as equivalent in the desalination industry has severe economic and environmental consequences. In the realms of the energy and desalination system planners, serious judgmental errors in the process selection of green installations are made unconsciously as the efficacy data are either flawed or inaccurate. Inferior efficacy technologies’ implementation decisions were observed in many water-stressed countries that can burden a country’s economy immediately with higher unit energy cost as well as cause more undesirable environmental effects on the surroundings. In this article, a standard primary energy-based thermodynamic framework is presented that addresses energy efficacy fairly and accurately. It shows clearly that a thermally driven process consumes 2.5–3% of standard primary energy (SPE) when combined with power plants. A standard universal performance ratio-based evaluation method has been proposed that showed all desalination processes performance varies from 10–14% of the thermodynamic limit. To achieve 2030 sustainability goals, innovative processes are required to meet 25–30% of the thermodynamic limit.