Investigation of a novel small-scale solar desalination plant (original) (raw)

Analysis of an innovative water desalination system using low grade solar heat

This paper presents a theoretical analysis and preliminary experimental results for an innovative water desalination system using low-grade solar heat. The system utilizes natural means (gravity and atmospheric pressure) to create a vacuum under which water can be rapidly evaporated at much lower temperatures and with less energy than conventional techniques. The system consists of an evaporator connected to a condenser. The vapor produced in the evaporator is driven to the condenser where it condenses and is collected as a product. The effect of various operating conditions, namely, withdrawal rate, depth of water body in the evaporator, temperature of the heat source, and condenser temperature, on the system performance were studied. Numerical simulations and preliminary experimental results show that the performance of this system is superior to a flat-basin solar still, and the output may be twice that of a flat-basin solar still for the same input. Vacuum equivalent to 4 Wa (abs) or less can be created depending on the ambient temperature at which condensation takes place.

Study of a water desalination unit using solar energy

Desalination and Water Treatment, 2009

This paper presents the study of a water desalination new design process working with the humidification-dehumidification (HD) method using solar energy. This process was developed in order to boost the productivity of the solar multiple condensation evaporation cycle unit which is located at the national school of engineering of Sfax, Tunisia, by integrating into the latter a flat-plate solar air collector and a humidifier. The HD process is essentially composed of a flat-plate solar air collector, a flat-plate solar water collector, a humidifier, an evaporation tower and a condensation tower. A general model based on heat and mass transfers in each component of the unit has been developed in a steady-state regime. The obtained set of ordinary differential equations has been converted to a set of algebraic system of equations by the functional approximation method of orthogonal collocation. The developed model is used to simulate the HD system in order to investigate the steady-state behavior of each component of the unit and the entire system exposed to a variation of the entrance parameters and meteorological conditions.

A new Solar Desalination System Design and Heat Recovery

Journal of Engineering Research, 2019

The work evaluates experimentally technique to improve fresh water production by careful energy recovery in the vapour condensation processes; the recovered heat in turn on drives additional evaporation and preheats the feedwater. A pilot plant is designed and constructed in an arid area with 2 m 2 solar evaporation collector area to evaluate the process. This unit is tested on cold and hot days. The effect of main parameters on fresh water production of the unit is studied. The experimental results show that, the production rate and efficiency of the system are strongly affected by solar radiation and level water in solar evaporation collector. Within the studied ranges, the maximum productivity reached to 16.1 kg/ m 2 day at Tvap,av = 87.6 o C , solar radiation 842 W/m 2 and level water 1.912 kg. According to these results, fresher water production of the present system is higher than that solar still desalination system in the previous studies.

Experimental Study of a Solar Thermal Desalination Unit

Volume 6B: Energy, 2013

Scarcity of potable water causes a serious problem in arid regions of the world where freshwater is becoming insufficient and expensive. Warm regions in the Middle East and North Africa are considered among the severest water shortage places. The objective of this project is to study the potential of using solar energy to run existing multi-stage flash (MSF) desalination units in the Arabian Gulf. One problem with MSF is the low efficiency of the system because of the bulk energy required for heating. Exploitation of solar energy in thermal desalination processes is a promising technology because of the ubiquitous nature of sun's energy. Experimental studies were conducted on a single flash desalination unit. The pilot unit demonstrates the use of solar radiation as the thermal energy input. The process starts by preheating seawater through a vacuumed condenser. Seawater, then, flows inside a circulation tank to be indirectly heated by a heat transfer fluid. The heat transfer fluid circulates inside a flat plate solar collector facing south to absorb solar energy. After raising its temperature, seawater goes through an expansion valve and flashes in a vacuumed chamber to form brine and vapor. The vapor transfers to the condenser and condenses to form potable water by losing its latent heat of vaporization to incoming seawater. The flow rate of the working fluid is controlled via a control valve based on a set point temperature reference. The experiments were carried out using different values of the controlling variables to enhance analysis and validate results.

Design and experimental analysis of solar water desalination system

2013

There is almost no water left on earth that is safe to drink without purification after 20-25 years from today. This is a seemingly bold statement, but it is unfortunately true. Only 1 % of Earth's water is in a fresh, liquid state, and nearly all of this is polluted by both diseases and toxic chemicals. For this reason, purification of water supplies is extremely important. Keeping these things in mind, we have devised a model which will convert the dirty/saline water into pure/potable water using the renewable source of energy (i.e. solar energy). The basic modes of the heat transfer involved are radiation, convection and conduction. The results are obtained by evaporation of the dirty/saline water and fetching it out as pure/drinkable water. The designed model produces 1.5 litres of pure water from 14 litres of dirty water during six hours. The efficiency of plant is 64.37%. The TDS (Total Dissolved Solids) in the pure water is 81ppm.

Studies on a single-stage solar desalination system for domestic applications

Desalination, 2005

In this paper, an attempt has been made to study a single stage solar desalination system to get a daily yield of 10 1 of potable water. The experimental system consists of a flat plate collector, an evaporator, a single stage vacuum pump and a condenser. The input parameters such as solar irradiance and vacuum pressure in the flash evaporator are varied to find its influence on the performance output viz., system efficiency and yield per day. Efficiency of this plant is found to vary from 15% to 26% for the variation in beam solar radiation from 400 W/m2 to 900 W/m2. A maximum distillate yield of 8.5 1/d is obtained with collector area of 2 m2. The frequency of operation of the vacuum pump and the yield of desalinated water for various beam solar radiations is carried out from which the cost of water is determined. The cost of desalinated water is found to be 0.9 e/l. The desalinated water is tested for various parameters and the results indicate that the quality of water is satisfactory and well below the permissible limits.

Design and experimental analysis of solar water desalination system Engineering

2013

There is almost no water left on earth that is safe to drink without purification after 20-25 years from today. This is a seemingly bold statement, but it is unfortunately true. Only 1% of Earth's water is in a fresh, liquid state, and nearly all of this is polluted by both diseases and toxic chemicals. For this reason, purification of water supplies is extremely important. Keeping these things in mind, we have devised a model which will convert the dirty/saline water into pure/potable water using the renewable source of energy (i.e. solar energy). The basic modes of the heat transfer involved are radiation, convection and conduction. The results are obtained by evaporation of the dirty/saline water and fetching it out as pure/drinkable water. The designed model produces 1.5 litres of pure water from 14 litres of dirty water during six hours. The efficiency of plant is 64.37%. The TDS (Total Dissolved Solids) in the pure water is 81ppm.

Stand-alone solar desalination plant

2007

The paper presents research to design and develop an efficient stand-alone modular desalination system able to provide sufficient non potable water to satisfy the needs of an average family of four living in Mediterranean regions. The system comprises a solar thermal collector for providing thermal energy for the desalination process and photovoltaic (PV) elements to provide electrical energy for the pumping operations. The analysis given here starts by presenting the functional scheme of designing a multi-stage flash (MSF) desalination thermal plant where the saltwater is warmed to about 90°C and supplied to several chambers in turn, where the pressure reduces sequentially from one space to the next. It is clear from the analysis that the plant requires large surfaces to provide sufficient evaporation of the seawater; in view of this, an alternative approach based on using several spray-nozzles together with only one flash chamber is proposed. This substantially improves the heat exchange between the seawater and the internal air for the evaporation of the saltwater. The electric power to pump the seawater supply through the solar collector and through the spray nozzle as well as the pumping requirements of the fresh water and brine extracting pumps will be supplied by PV panels. The surface area of the thermal collector will be about 6 m 2 with an optimal tilt angle for summer.