一种岛礁用结合压汽蒸馏的太阳能海水淡化装置<br>A Solar Energy Distiller Combined with Vapor-Compress Plant for Seawater Desalination

Processing of liquid radioactive waste (LRW) includes evaporation followed by vitrification. Reducing the energy consumption of evaporation of LRW is an urgent task. In the article, an attention is paid to the fact that similar technical and economic problems are solved with the desalination of seawater. It is proposed to use well-developed seawater desalination technologies for preliminary evaporation of LRW. For a detailed analysis, desalination technology with mechanical vapor compression (MVC) was selected. This technology is energy-saving because it implements the heat pump principle. MVC technology is highly efficient, simple, and does not lead to the generation of secondary radioactive waste. A mathematical model of a single-stage desalination plant with MVC has been developed, taking into account that the thermodynamic cycle of this process is open. Since there are no data on the physical properties of LRW in the literature, the properties of sea water were used. The design and operational parameters were optimized in order to reduce the cost of 1 m3 of evaporated water. It has been established that the main design parameters affecting the cost of evaporated water are the degree of vapor compression in the compressor and the heat exchange surface area of the evaporatorcondenser. The influence of these parameters on capital and operating costs is shown. The optimal combinations of these parameters are determined. To ensure the optimal operating mode of the installation, it is necessary to maintain the optimum salt content of boiling brine, which is determined by the rate of consumption of the source water. The optimal values of these parameters are calculated in a wide range of salt content of the source water. It is shown that, at low salinity of the initial LRW, evaporation is advisable to be carried out in a multi-stage installation. As a result of the calculations, it was found that the specific cost of evaporation of liquid radioactive waste with an initial salt concentration of 10% to a salt content of 20% using the desalination technology with mechanical vapor compression is 0.843 USD/m3.

The influence of operation parameters on concentration ratio of multi-effect evaporation system with mechanical vapor compression

PV and CSP solar technologies & desalination: economic analysis

Energy/exergy analysis of solar driven mechanical vapor compression desalination system with nano-filtration pretreatment

The multi-generation systems with simultaneous production of power by renewable energy, in addition to polymer electrolyte membrane electrolyzer and fuel cell (PEMFC-PEMEC) energy storage, have become more and more popular over the past few years. The fresh water provision for PEMECs in such systems is taken into account as one of the main challenges for them, where conventional desalination technologies such as reverse osmosis (RO) and mechanical vapor compression (MVC) impose high electricity consumption and costs. Taking this point into consideration, as a novelty, solar still (ST) desalination is applied as an alternative to RO and MVC for better techno-economic justifiability. The comparison, made for a residential building complex in Hawaii in the US as the case study demonstrated much higher technical and economic benefits when using ST compared with both MVC and RO. The photovoltaic (PV) installed capacity decreased by 11.6 and 7.3 kW compared with MVC and RO, while the size of the electrolyzer declined by 9.44 and 6.13%, and the hydrogen storage tank became 522.1 and 319.3 m3 smaller, respectively. Thanks to the considerable drop in the purchase price of components, the payback period (PBP) dropped by 3.109 years compared with MVC and 2.801 years compared with RO, which is significant. Moreover, the conducted parametric study implied the high technical and economic viability of the system with ST for a wide range of building loads, including high values.

Globally, about 10% of the world population does not have access to enough fresh water. In many hot-and-dry coastal regions and islands, the desalination of seawater might be the only practical option to have a fresh water supply. Therefore, low-cost desalination system is critical for freshwater demands. To address this issue, a desalination system consisting of solar photovoltaic (PV) and mechanical vapor compression subsystem is proposed in this study. The entire desalination system was modeled and designed to produce 10,000 m3 of fresh water per day at the coast of San Francisco, California. Key components such as water vapor compressor, solar PV panel, and three-stream heat recovery unit were designed, and their performances were analyzed. The effects of design variables and operating conditions on the system performance were investigated through a parametric study. Finally, an economic analysis was conducted and compared with current desalination technologies. The analysis results show that the specific power consumption of desalination system can reach 14.4 kWh/m3 when the evaporation temperature is 70°C. It is found that the evaporating temperature has a great influence on the heat pump system efficiency and evaporator design. The levelized cost of the proposed system is $0.76 per m3 of fresh water which is lower than current grid-powered vapor compression desalination system and other thermal desalination systems. The proposed solar PV driven desalination improves thermoeconomics of desalination system by applying low-lift operating condition to the vapor compression cycle so that it can contribute to solving the fresh water supply challenges.

The paper aims to investigate how to improve the performance of a refrigeration system (Rs) that equips a cold room, by incorporating phase change materials (Phase Change Materials - PCMs) in these systems, a study that has not yet been extended experimentally. The study is carried out on a cold room within the National University of Science and Technology Politehnica Bucharest - Faculty of Mechanical and Mechatronics Engineering, Department of Thermodynamics, Engines, Thermal and Refrigeration Equipment. This room is equipped with a refrigeration system with mechanical vapour compression (VCRs), which uses R404A as refrigerant. Mechanical vapour compression refrigeration system (VCRs) with an evaporation temperature below 0 oC causes ice to form on the evaporator leading to reduced performance. Currently, the widely used methods for defrosting are the standard methods, the most used being the electric one, which of course consumes energy. This paper aims to evaluate the availability of heat that could be used in the defrosting process by means of PCMs. The study was made using the Engineering Equation Solver software, several types of PCMs and also different refrigerants (R600a, R600, R1234yf, R1234ze, R152a, R290, R32) and in this way it was intended to identify the right agent to be used for a particular type of PCM. Faculty of Mechanical and Mechatronics Engineering, Department of Thermodynamics, Engines, Thermal and Refrigeration Equipment

The indirect evaporative cooler (IEC) is deemed an effective and sustainable alternative to existing mechanical vapor compression (MVC) chillers in cooling applications. However, IEC is a passive cooler that has no effective control over the supply air temperature and humidity. Also, the performance of IEC degrades severely when the humidity of the air is high. To overcome these limitations, we investigate a hybrid process that connects IEC and MVC in tandem. The outdoor air is firstly pre-cooled in the IEC by recovering energy from the room exhaust air, and then it is further processed to the desired condition using MVC. Such a hybrid IEC-MVC process benefits from IEC’s high energy efficiency and MVC’s capability of humidity and temperature control. A pilot IEC unit with the cross-flow configuration is firstly constructed and tested under assorted outdoor air conditions. Employing the room exhaust air as the working air in the wet channels, the IEC simultaneously cools and dehumidifies the outdoor air. Under the operating conditions considered, the outdoor air temperature can be reduced by 6–15 °C, and the humidity ratio drops by 0.5–4 g/kg. The coefficient of performance (COP) for IEC is 6–16, leading to an overall COP of 4.96–6.05 for the hybrid IEC-MVC process. Compared with a standalone MVC, the electricity consumption can be reduced by 19–135%.

Performance study on a mechanical vapor compression evaporation system driven by Roots compressor

A review of recent advances in humidification and dehumidification desalination technologies using solar energy

Transient model, simulation and control of a single-effect mechanical vapour compression (SEMVC) desalination system

Biomass-derived porous carbon for excellent low intensity solar steam generation and seawater desalination

Power and freshwater demand are increasing as populations around the world keep growing. Due to the environmental impact of using fossil fuels and limited resources, using solar thermal in desalination application is a valuable option. In this paper, an innovative new design of low-temperature multi-effect desalination coupled with mechanical vapor compression (LT-MED-MVC) powered by supercritical organic Rankine cycle (SORC) utilizing a low-grade solar heat source using evacuated tube collectors is analyzed. The proposed design has the potential to desalinate water of high salt concentrations or brine with high salinity more than 100,000 ppm or effluent streams from a power plant with low energy consumption and high efficiency when compared to other systems. The performance of the LT-MED-MVC was found to be better than similar systems found in the literature. The specific power consumption for the system is lower than 4 kW h/m3 for seawater feed salinity of 100,000 ppm, 14 forward feed effects, and a recovery rate of 50%. The overall system efficiency is about 14%. The impact of increasing the number of effects, motive steam temperature, pressure of SORC, and salt concentration on the specific power consumption, solar collector area, and the system efficiency are also analyzed.

High temperature heat pumps (HTHPs) are essential technology for the electrification of industrial thermal processes. However, their widespread deployment is conditioned by the development of a framework for selecting the optimal HTHP configuration and refrigerant. In this paper, thermodynamic models are developed for estimating the performance of various HTHP configurations: single-stage, two-stage, cascade, Joule-Brayton, mechanical vapor re/compression HTHPs working with low-GWP refrigerants. The results are used to construct a new map of HTHP performance and selection. This represents a systematic, concise, and visual framework to guide the selection of the appropriate HTHP configuration that achieves a high COP for a given temperature lift and of the refrigerant that maximizes the COP. The map illustrates the influence of temperature conditions and the limitations imposed by compressors and refrigerants. Joint evaluation of HTHP configuration, refrigerant, and compressor technology extends achievable temperatures (evaporation temperature between 10°C and 90°C, condensation temperature up to 250°C for closed vapor compression cycles, and up to 350°C for open vapor compression cycles, and maximum temperature above 500°C for gas compression cycles). Additionally, centrifugal compressors are shown to be applicable in HTHPs, considering the limitations in impeller peripheral speed (for refrigerants with small molecular mass) and fluid flow Mach number (for refrigerants with large molecular mass), as well as their implications on the achievable temperature lift. This indicates that high heating capacity HTHPs can be realized. An original system design diagram of industrial multi-energy systems shows the appropriate application of different HTHP configurations across suitable temperature levels. • Joint evaluation of HTHP configurations, refrigerants, and compressor technology • Closed cycle, mechanical vapor compression and recompression, and Joule-Brayton HTHP • Compressor imposed limitations on the pressure ratio and temperature lift • Map of performance and selection of a HTHP and refrigerant based on temperature lift • HTHP-integrated MES for process heat electrification under limited grid capacity

The problem of fresh water lack can be solved my desalination of the seawater. Desalination of the seawater can be accomplished by several methods. Distillation of the seawater is one of the most promising among them. Comparative analysis of distillation desalination plant requires certain criteria. This criterion must take into account both energy consumption and seawater salinity. Relation of the minimal work required for seawater desalination to energy consumption was selected as such criterion. Four types of the distillation plants were considered: Multi-effect distillation plants (MED), multi-effect distillation plants with mechanical vapor compression (MVC) plants, MVC desalination plants have the best multi-effect distillation plant with thermal vapor compression (TVC) plants and Multistage flash distillation plants (MSF). MSF plants gave dependency that their efficiency rise along the gain ratio. That may be explained by the fact that its steam consumption does not depend on seawater consumption. TVC plants have slightly higher efficiency than MED plants. Thus, MVC plants can be recommended to use if there is no heat source, MSF plants - if there is heat source and plant must have a high gain ratio and TVC plant in the rest cases.