•A new geothermal combined cooling, heating and power system is proposed.•A new method to recover waste heat of absorption refrigeration cycle is proposed.•The components prone to generate exergy ...destructions in the system are discovered.
In this paper, a new geothermal combined cooling, heating and power system that integrates flash power cycle and ammonia-water absorption refrigeration cycle, is proposed to supply electricity, refrigerant water and domestic hot water simultaneously to users. In the system, the refrigeration cycle serves as the bottom cycle of the power cycle by further utilizing the exhausted geothermal water from the flasher of the power cycle, meanwhile all waste heat of the power and refrigeration cycles is recovered for supplying heat, thus effectively improving the energy conversion efficiency of whole system. This paper establishes detailed mathematical models of the proposed system and conducts a valid model validation. Then a preliminary design condition of the system is given and the results show that the exergy efficiency of system could reach 43.69% under the condition of 170 ℃ geothermal water. An exergy loss analysis is carried out based on the design condition, demonstrating that the maximal exergy destruction exists in the condenser of flash cycle, accounting for 48.53% of the total exergy destruction of the system; the components used for separating or mixing fluids including rectification column, absorber and flasher, occupying 17.68%, 9.02% and 9.30% respectively, are prone to generate exergy destructions. Finally a thermodynamic parameter analysis, in order to assess the effects of seven key parameters on the system performance, is performed. The results show that there are an optimal flash pressure (about 300 kPa) and an optimal generator temperature (about 120 ℃) respectively that could make the exergy efficiency of system maximal. Within some scopes, lower turbine back pressure and rectification column pressure, higher ammonia concentration of ammonia-strong solution, bring about higher exergy efficiency of system. Additionally the evaporation pressure and the reflux ratio of rectifier just make little difference on the exergy efficiency of system.
The separation of oil from oily water is an important pursuit because of increasing worldwide oil pollution. Separation by the use of materials with selective oil/water absorption is a relatively ...recent area of development, yet highly promising. Owing to their selective superantiwetting/superwetting properties towards water and oil, superhydrophobic/superoleophilic surfaces and underwater superoleophobic surfaces have been developed for the separation of oil/water‐free mixtures and emulsions. In this Review, after a short introduction to oil/water separation, we describe the principles of materials with selective oil/water absorption and outline recent advances in oil/water separation with superwetting/superantiwetting materials, including their design, their fabrication, and models of experimental setups. Finally, we discuss the current state of this new field and point out the remaining problems and future challenges.
Stringent segregation: Superhydrophobic/superoleophilic surfaces and underwater superoleophobic surfaces have been successfully designed, fabricated, and employed in the separation of oil/water‐free mixtures and emulsions on the basis of their selective superantiwetting/superwetting properties towards water and oil. Progress, remaining problems, and future challenges in this field are discussed in this Review.
•The hygrothermal properties of BC-contained pervious concrete that were investigated.•Biochar could improve the water absorption capability of pervious concrete.•BC-contained pervious concrete ...demonstrated a better cooling performance.
Pervious concrete is regarded as a contributing material to reduce surface runoff, purify water pollution, and mitigate the urban heat island. However, the poor water absorption and retention capabilities of it could not meet the need of evaporation. To prolong its evaporative cooling effect, this study introduces a modified method of incorporating biochar (BC) particles into pervious concrete as hygroscopic filler. The albedo, emissivity, porosity, microstructure morphology, water absorption, and evaporation of pervious concrete that was prepared by replacing the cement in weight, by 5.0% of BC particles were investigated. It was found that the BC addition had little impact on the emissivity and porosity of pervious concrete, while significantly reduced the albedo. Contributing to the abundant micro-pores and higher specific surface area of carbonaceous particles, they would significantly enhance the water absorption and retention capability of pervious concrete. Using 5.0% pulverized BC as the admixture maximally increased the total water absorption of pervious concrete from 100 ± 2 kg/m3 to 117 ± 8 kg/m3. During the evaporation process, the water absorption increment could effectively decrease the surface temperature by up to 3–6 °C, with an extra cooling period of 6 h, compared to conventional BC-free pervious concrete. Based on the findings, we conclude that replacing a small quantity of cement by pulverized BC in conventional pervious concretes could effectively improve the evaporative cooling performance.
This study aims to verify the predictability of selected measured properties of soil
and plants at depletion rates of available water and the use of soil conditioners
using the root zone water ...quality model RZWQM2. A field experiment was conducted to cultivate the Cabbage crop for the autumn of 2021 at the field experiment
station F / College of Agricultural Sciences in Al-Jadiriyah region, Baghdad- Iraq.
The effect of depletion rates of available water and the addition of soil conditioners
on dry weight, yield, water consumption, reference and potential evapotranspiration, water absorption by the plant, and the crop water use efficiency of the Cabbage plant was evaluated using the model RZWQM2. The experiment treatments
were: D1: Irrigation after depleting 30% of available water, D2: Irrigation after
depleting 60% of available water, C0: without addition, C1: adding organic matter
(Compost) 20 Mg.ha-1, C2: adding perlite 4 Mg.ha-1, C3: adding organic matter
(Compost) 10 Mg.ha-1 + perlite 2 Mg.ha-1. A scenario was created in the
RZWQM2 model to simulate the studied traits at field conditions. The results
showed that the percentage of depleting 30% of available water was better than the
percentage of depleting 60% of available water using the RZWQM2 model at dry
weight, yield, water consumption, reference, and potential evapotranspiration, water absorption by the plant, and the crop water use efficiency of the Cabbage plant.
Also, the treatment of adding compost exceeded the rest of the conditioners and
the comparison treatment at depletion rates of 30 and 60% of available water in the
measured properties. Furthermore, adding compost reduced water consumption
compared to the rest of the study treatments.
Keywords: predictability; Irrigation; water absorption; evapotranspiration.
•A novel combined cooling, heating and power system driven by solar energy is proposed.•It is determined that a high exergy destruction rate occurs in the solar collectors.•The cogeneration heat and ...power efficiency reaches to 96.0%.
A novel combined cooling, heating and power system (CCHP) driven by solar energy is proposed. The system applies an organic Rankine cycle, a double effect lithium bromide-water absorption refrigeration system, and heat exchangers to generate electricity, cooling and heating, respectively. Energy and exergy analyses are conducted to determine system efficiencies and losses. The cycle is compared with similar combined cycle that differs by using a cooling subsystem having a single effect absorption chiller. The effects of some key thermodynamic parameters on the performance of the cycle are examined. The results reveal that, for the same amount of input heat, the usage of a double effect absorption refrigeration system instead of a single effect absorption chiller can raise the amount of cooling power up to 48.5% and consequently can improve the performance of the system. At the same time, heating power rises by 20.5%, resulting in an increase in the cogeneration heat and power efficiency to 96.0%, while net electrical power production declines by 27%. In addition, it is determined that a high exergy destruction rate occurs in the solar collectors.
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Oily water treatment has become an urgent need in our daily life because of its harmful potential to the ecological system. In recent years, functional materials with superwetting or ...superantiwetting property have experienced a rocketing development due to their applications in various areas, including self-cleaning, anti-icing, printing, water collection, liquid transfer, oil/water separation, and so on. In this regard, recent advances in polymer science hold the promise of fine-tuning the composition and morphology for a targeted design to meet the requirements in specific application fields. This review focused on polymeric materials, especially smart polymers, for controllable oil/water separations. Starting from the fundamental theories and criteria related to the separation mechanisms, different stimuli including pH, solvent, ions, chemicals, temperature, photo, electric, pressure, and dual stimuli for triggering smart oil/water separation processes were summarized. Highlights on polymer types, polymer synthesis approaches, separation materials fabrication method, as well as separation performances were present. Current limitations and future perspective were also given. This review aims to offer deep insights into polymer-based interfacial science and provide guidance for the fabrication of smart polymeric surfaces for oily water separation.
Drought stress imposes a serious threat to crop productivity and nutritional security. Drought adaptation mechanisms involve complex regulatory network comprising of various sensory and signaling ...molecules. In this context, melatonin has emerged as a potential signaling molecule playing a crucial role in imparting stress tolerance in plants. Melatonin pretreatment regulates various plant physiological processes such as osmoregulation, germination, photosynthesis, senescence, primary/secondary metabolism, and hormonal cross‐talk under water deficit conditions. Melatonin‐mediated regulation of ascorbate‐glutathione (AsA–GSH) cycle plays a crucial role to scavenge reactive oxygen species generated in the cells during drought. Here, in this review, the current knowledge on the role of melatonin to ameliorate adverse effects of drought by modulating morphological, physiological, and redox regulatory processes is discussed. The role of melatonin to improve water absorption capacity of roots by regulating aquaporin channels and hormonal cross‐talk involved in drought stress mitigation are also discussed. Overall, melatonin is a versatile bio‐molecule involved in growth promotion and yield enhancement under drought stress that makes it a suitable candidate for eco‐friendly crop production to ensure food security.
•The recycled sand employed into the mix of 3D printed mortar and the green strength development at early ages was explored.•Recycled sand has significant effect on the early age behavior for those ...mature specimens.•The addition of recycled sand will change the mortar from plastic material to solid material in the later stage.
One of the technical challenges for the extrusion-based 3D printed concrete is that the requirements of green strength development are much different from ordinary concrete, due to the absence of formwork. This study employed the recycled sand into the mix of 3D printed mortar and explored the green strength development at early ages within 2.5 h after extrusion. 25% and 50% natural sand was replaced by recycled sand which was crushed from waste concrete in the mix. Uniaxial unconfined compressive tests were undertaken to obtain the mechanical properties of the printable mortar, while the failure patterns, vertical load–displacement relationship, lateral deformation and stress–strain behavior were recorded and fully analyzed. It is found that the recycled sand had very limited influence for those immature specimens, while exerted significant effect on the early age behavior for those mature specimens. The addition of recycled sand will change the mortar from plastic material to solid material, especially when the rest time reaches 90 min after the extrusion. It is believed that the high cement paste content and large water absorption of recycled sand in the 3D printed mortar affects the early age behavior. Since the incorporation of recycled sand improves the buildability while reduces the open time of the printed material, it is necessary to reasonably adjust the mix ratio and the amount of recycled sand in practical printing.
•The heat and mass transfer performance of a novel absorber was investigated.•The experimental was conducted under realistic working conditions.•The heat and mass correlations were developed with ...error bands of ±15%.•A high heat flux per unit volume can be achieved by the novel absorber.
Compact absorber is beneficial for bulk reduction and cost-saving of absorption systems. This paper presents an experimental study on the heat and mass transfer performance of a novel absorber which consists of an S-shaped capillary coils bundle. Experiments were carried out for a practical ammonia-water absorption system under practical working conditions. The effects of operating parameters such as degree of subcooling, concentration and mass flow rate of inlet solution, as well as absorption pressure, on absorption were investigated. Specifically, with the selected pressures of 300kPa, 400kPa and 500kPa and concentrations of inlet solution of 6.6%, 15.5% and 22.4%, we obtained the heat and mass transfer coefficients ranging from 622~1945 Wm-2K-1 and 5.1~34.3×10-6 ms-1, respectively. The heat and mass transfer experimental data were processed in terms of the empirical correlations for the Nusselt and Sherwood numbers, respectively, and the correlations can fit all the experimental data with error bands of ±15%.
Extensive amounts of ceramic and slag wastes are produced every year by ceramic and iron industries. Recycling of these wastes are one of the operational solutions to eliminate their disposal. It is ...appropriate to employ these wastes as a binder material in the field of construction to save the virgin natural raw materials and limit environmental pollution problems. This work aims to incorporate ceramic waste powder (C–W–P) into alkali-activated slag (AAS) pastes activated with sodium silicate. The specimens were cured at a high ambient temperature of 45 °C to simulate curing in hot weather. Slag was partially replaced with C–W–P in the range of 5–50%, by weight. The effect of C–W–P on the workability, water absorption and compressive strength were measured. After 91 curing days, some specimens were subjected to elevated temperatures in the range of 200–1000 °C with a step of 200 °C for 2 h and the residual compressive strength was monitored. The results were analyzed by X-ray diffraction (XRD), thermogravimetric analysis and its derivative (TGA/DTG) as well as scanning electron microscopy (SEM). The results revealed that C–W–P has a negative effect on the workability, whilst it has a positive effect on the water absorption as well as the compressive strength before and after exposure to elevated temperatures.
•Curing in a hot weather can affect the compressive strength development.•C–W–P has a negative and positive effect on the workability.•C–W–P has a positive effect on water absorption.•C–W–P increased AAS pastes compressive strength before and after heating.
