https://orcid.org/0000-0002-1948-8785
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ABSTRACT
The aim of this work is to design and analyze solar humidification and dehumidification desalination plant that is integrated with an energy tower. The proposed integrated water production plant (IWPP) utilizes the waste humid air of the energy tower for the production of potable water as an added benefit in bonus apart from the power production through energy tower. The layout of the proposed desalination plant has been presented which is configured with 100 solar humidification dehumidification desalination units and capable to fulfill potable water demand of 800 liters per day that may be sufficient for a small community of remote area. The seasonal and annual performance of the plant has been analyzed in the climatic condition of Jamnagar which is hot and humid city in western Indian state, Gujarat. The optimum values of air and water mass flow rate have been identified with the help of mathematical simulations in summer, rainy and winter season. The results showed that air mass flow rate 118–120 kg/hr through solar air heater is suitable for water production throughout the year. The water mass flow rate of 125–130 kg/hr in humidifier and 120 kg/hr−122 kg/hr in dehumidifier has been found optimum for potable water production. The seasonal variation in gain output ratio is 0.32−0.45 however it can be increased to 0.62 at optimized operating condition. Finally, the economic and environmental analysis of the proposed plant resulted Rs 0.93/kg (US $ 0.011/kg) cost of potable water, payback period of 0.49 year and 146.8 t/annum reduction in CO2 emission, respectively.
HIGHLIGHTS
Mini desalination plant capable to fulfill water needs of small community.
Utilization of waste humid air of energy tower
Clean source of potable water.
Numerical analysis for time dependent behavior.
Annual performance, economic and environment analysis.
Nomenclature
| Ah | = | Area of solar air heater (m2) |
| C | = | Convection |
| Ca | = | Specific heat of air (J/kg-K) |
| Cb | = | Specific heat of base plate (J/kg-K) |
| Cg | = | Specific heat of glass cover (J/kg-K) |
| Cp | = | Specific heat of absorber plate (J/kg-K) |
| Cw | = | Specific heat of water (J/kg-K) |
| h | = | Convective heat transfer coefficient (W/m2K) |
| h’a2out | = | Enthalpy of air at humidifier inlet (J/kg) |
| h’a3 | = | Enthalpy of air at humidifier outlet (J/kg) |
| h’a4 | = | Enthalpy of air at dehumidifier outlet (J/kg) |
| hfg | = | Latent heat of vaporization (kJ/kg) |
| ka | = | Thermal conductivity of air |
| l | = | Length of solar air heater (m) |
| ma | = | Mass of air (kg) |
| mb | = | Mass of base plate (kg) |
| mg | = | Mass of glass cover (kg) |
| mp | = | Mass of absorber plate (kg) |
| mws | = | Mass of water in storage tank (kg) |
| Ma | = | Mass flow rate of air (kg/s) |
| Mc | = | Mass flow rate of condensate water (kg/s) |
| Mmw | = | Mass flow rate of makeup water (kg/s) |
| M1 | = | Mass flow rate of water at humidifier inlet (kg/s) |
| M2 | = | Mass flow rate of water at humidifier outlet (kg/s) |
| M3 | = | Mass flow rate of cooling water at dehumidifier inlet (kg/s) |
| Q | = | Rate of heat transfer (W) |
| Qin | = | Total heat input to system (W) |
| R | = | Radiation |
| Sair | = | Solar insolation absorbed by air (Watt) |
| Sg | = | Solar insolation absorbed by glass cover (Watt) |
| Splate | = | Solar insolation absorbed by absorber plate(Watt) |
| Ta1 | = | Temperature of air in first pass (K) |
| Ta2 | = | Temperature of air in second pass (K) |
| Tb | = | Temperature of base plate (K) |
| Tg | = | Temperature of glass cover (K) |
| Tmw | = | Temperature of makeup water (K) |
| Tplate | = | Temperature of absorber plate (K) |
| Tws | = | Temperature of water in storage tank (K) |
| T1 | = | Temperature of water at humidifier inlet (K) |
| T2 | = | Temperature of water at humidifier outlet (K) |
| T3 | = | Temperature of cooling water at dehumidifier inlet (K) |
| T4 | = | Temperature of cooling water at dehumidifier outlet (K) |
| T5 | = | Temperature of condensate water (K) |
| Vi | = | Wind speed (m/s) |
| w1 | = | Moisture content at humidifier inlet |
| w3 | = | Moisture content at humidifier outlet |
| w4 | = | Moisture content at dehumidifier outlet |
| wET | = | Moisture content at energy tower outlet |
| wamb | = | Moisture content of ambient air |
| W | = | Width of solar air heater (m) |
| α | = | Absorptivity |
| τ | = | Time (sec) |
| εg | = | Emissivity of glass cover |
| εplate | = | Emissivity of absorber plate |
| εbase | = | Emissivity of base plate |
| A.C. | = | Annual cost |
| A.A.T.C. | = | Annual Actual total cost |
| A.O.C | = | Avarage operating cost |
| A.S.V. | = | Annual Salvage value |
| C.R.F | = | Capital recovery factor |
| C.O.P.W. | = | Cost of potable water |
| ET | = | Energy Tower |
| GOR | = | Gain output ratio |
| HD | = | Humidification– dehumidification |
| IWPP | = | Integrated water production plant |
| M.C. | = | Annual maintenance cost |
| S.V. | = | Salvage value |
| T.I.C. | = | Total investment cost |
Disclosure statement
No potential conflict of interest was reported by the author(s).