Air to Water Generator Integrated System Real Application: A Study Case in a Worker Village in United Arab Emirates
- the case study described by authors in ref. , which provided a methodological approach refined and used in the current study;
- the experience reported in ref. , which used the same machine subject of the current work but only for water quality analyses purposes;
- the test performed in ref. , where it was tried to improve the water yield, increasing the vapour content in the air by means of adiabatic cooling.
- more data about large-sized integrated AWG real tests;
- HVAC retrofitting potentialities by means of integrated AWG;
- extended economic evaluations, taking into account the water quality and the particularity of the integration (HVAC contributions);
- considerations about plastic saving.
- the machine behaviour during an entire year, tuning the physically based model used in ref. ;
- revamping potentialities of the existing HVAC plant;
- economic analyses, carried out considering the integration advantages and the quality of the produced water;
- plastic savings potentialities.
2. AWG Technologies
- a certain quantity of condensed water;
- a cooled and dried airflow that can be directly employed as primary air or convoyed into an Air Handling Unit (AHU) of an air conditioning system;
- a flux of heating energy, which can be used to heat up, for example, domestic water.
- Data collection: the case study section reports information about the test site and the characteristics of the possible buildings to be served by the integrated machine. Moreover, needs about drinking water, primary air and thermal heating for domestic water were described too. Data concerning the existing plants were also collected, as well as costs about drinking water and energy sources.
- Weather environmental conditions: statistical hourly data about temperature and relative humidity from a weather station placed in Dubai, at only 5 km from the installation spot, were collected in order to have the climatic conditions of an entire statistical year. A brief analysis of the weather data frequency was also added.
- Integrated system behaviour analyses: the behaviour of the machine, installed nearby the kitchens building, was monitored by the data collection in some time periods. On the basis of such data, the simulator, used in ref. , was fine-tuned and run using the Dubai climate conditions, collected by means of the said weather station in order to determine how the machine was expected to behave all over the year in terms of produced water, energy consumption, heating power/energy and cooling power/energy. In order to evaluate the energy efficiency of the machine, in terms of produced water and consumed energy, the Water Energy Transformation (WET) indicator was employed .
- Covered needs: matching the integrated machine behaviour in the Dubai weather and the needs (drinking water, primary air and domestic water heating), it was calculated how many buildings it was possible to serve.
- Economic evaluations: all the voices, positive and negative, related to the machine installation and its use, were collected and the Pay Back Time (PBT) calculated. Moreover, the Net Present Value and the actualised Pay Back Time were calculated, because the installation can be seen as a sort of investment.
- plastic savings: on the basis of the literature data, savings in terms of avoided plastic bottles were calculated.
4. Case Study
4.1. Geographical Site, Buildings, Existing Plants and Energy and Water Supply
4.2. Bottled Water Cost
4.3. Electricity Cost
4.4. LPG Cost
4.5. Weather Conditions
5. Integrated Machine: Description, Plant Linking and Behaviour Analyses
5.1. Integrated Machine Description
- Air filters placed in the inlet section. The air coming from the environment is cleaned by means of a filtration stage composed by two filter arrays in series: the first composed by coarse filters followed by pocket filters in order to avoid pollution due to dust, sand, insects, bacteria and other particles.
- Evaporation and heat recovery coils. The cooling process is carried out by means of direct cooling on an evaporation coil combined with a heat recovery system. Both of them are made of food contact materials . The airflow, after the cooling process, can be collected in a duct in order to be delivered to zones requiring cooled and dry air changes.
- Evaporation fans. The machine has centrifugal evaporation fans that can provide an average airflow, in Dubai conditions, of 10,000 m3/h.
- Screw Compressor. The compressor running the thermodynamic reverse cycle is a screw compressor having, in Dubai environmental conditions, an average cooling and heating capacity, respectively, of 81 kW and 105 kW. The coolant is R134a.
- Condensation coils. The machine is equipped by two kinds of condenser: a finned air-cooled coil and a plate heat exchanger. The condensation heat is delivered to the domestic water by means of this second condenser, where the water flow is run by a pump, regulated by the setting temperature. When heating is not required, the condensation is provided by the fined coil, cooled by the environmental air. The plate heat exchanger works with a classic temperature difference of 5 °C. The domestic water heating was set to obtain a temperature difference of 40 °C and a maximum temperature of 50 °C.
- Water treatment unit. The condensate coming from the evaporator is collected in a tank in stainless steel. After that, the liquid is processed in a multistage system comprising mechanical filtration made by three stages with decreasing meshes, the last one having a mesh of 1 μm, activated carbon filter, adsorption resins, UV (ultraviolet) lamps, reverse osmosis and a mineralisation stage. The system is continuously monitored by means of a pH probe and a conductivity probe and a water meter dedicated to count the produced water.
5.2. Integrated Machine Plant Linking
5.3. Integrated Machine Behaviour and Needs Coverage
- It covers entirely the heating needs of domestic water of two residential buildings, substituting the electrical boilers and providing, in such a way, an electrical energy saving of 634,509.5 kWh/year, which is 100% of the whole energy consumption;
- It covers partially the kitchen heating needs of domestic water, providing an average of 70% of the required heating, leaving to the LPG boiler the residual heating work, giving, thus, LPG saving of 54,426.1 L/year;
- It helps the air conditioning system, providing a treated airflow and giving a cooling energy equal to 665,908.4 kWh, providing, in this case, an electrical energy saving of 190,259.5 kWh/year and 87% of the required fresh air.
6. Economic Evaluations
7. Plastic Saving
8. Discussion, Implications and Future Developments
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
|AED||ISO code for Dirham|
|AHU||Air Handling Unit|
|AWG||Air to Water Generator|
|AWH||Air Water Harvesting|
|COP||Coefficient of Performance|
|EER||Energy Efficiency Ratio|
|HVAC||Heating Ventilation Air Conditioning|
|ICP||Inferior Calorific Power|
|LPG||Liquid Petroleum Gas|
|NPV||Net Present Value|
|PBT||Pay Back Time|
|PLC||Programmable Logic Controller|
|WET||Water Energy Transformation|
|UAE||United Arab Emirates|
|a||dry air mass flow (kg/s)|
|C||water specific heat, 4.186 kJ/(kgK)|
|Cp||Inferior Calorific Power (kWh/L)|
|Cu||net cash flow (chosen currency)|
|en||energy (kWh) or (kJ)|
|ent||heating energy (kWh) or (kJ)|
|enel||electrical energy (kWh) or (kJ)|
|i||actualisation rate (%)|
|j||calculation model node number|
|m||water mass (kg)|
|N||time horizon (years)|
|q||water mass-flow (kg/s)|
|Qc||condensation energy (kJ)|
|R||coolant mass (kg)|
|r||coolant mass flow (kg/s)|
|R.H.||relative humidity (%)|
|t||dry bulb temperature (°C)|
|V(N)||residual value of the considered good at after the time horizon (chosen currency)|
|v||LPG volume (L)|
|τ||time period (year) or time step (s)|
|φ||energy flux (kW)|
|z||index of the mass flow or energy flow exchange in the node|
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|Physic Variable||Probe Type||Probe Error (in the Test Conditions)|
|Relative Humidity||Capacity hygrometer|
|±(1.3 + 0.003 measured r.h. value)%|
|Temperature||Resistance thermometer Pt100||±0.2 °C|
|Water flow||Oscillating piston water counter||±2% of the read value|
|Water weight||Electronic Pressure scale||±0.01 kg|
|Air Flow||Vane Anemometer||±1% of the read value or ±2% 0.02 m/s|
|Energy||Integrated Power meter||1% ± 2 words|
|Day of Test||Temperature||Relative Humidity||Water Production||Energy Consumption|
|Savings||Unitary Costs||Yearly Savings (EUR/Year)|
|LPG (L/year)||54,426.1||0.4484 EUR/L||24,405|
|Electricity due to boilers (kWh/year)||634,509.5||0.10384 EUR/kWh||65,887|
|Electricity related to air conditioning||190,259.5||19,757|
|Bottled water (L/year)||570,614.8||0.165 EUR/L||94,151|
|Costs||Unitary Costs||Yearly costs (EUR/year)|
|Integrated AWG machine electricity consumption (kWh/year)||331,775.2||0.10384 EUR/kWh||34,452|
|Maintenance and consumables (EUR/year)||12,000||-||12,000|
|Net revenue (EUR/year)||157,748|
|Starting investment (EUR)||292,163|
|Pay Back Time (years)||1.85|
|Electrical energy saving||85,644.0|
|Consumables and maintenance||−12,000.0|
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Cattani, L.; Cattani, P.; Magrini, A. Air to Water Generator Integrated System Real Application: A Study Case in a Worker Village in United Arab Emirates. Appl. Sci. 2023, 13, 3094. https://doi.org/10.3390/app13053094
Cattani L, Cattani P, Magrini A. Air to Water Generator Integrated System Real Application: A Study Case in a Worker Village in United Arab Emirates. Applied Sciences. 2023; 13(5):3094. https://doi.org/10.3390/app13053094Chicago/Turabian Style
Cattani, Lucia, Paolo Cattani, and Anna Magrini. 2023. "Air to Water Generator Integrated System Real Application: A Study Case in a Worker Village in United Arab Emirates" Applied Sciences 13, no. 5: 3094. https://doi.org/10.3390/app13053094