Atmospheric water generation system

The development of the system for the Customer commenced with an analysis of existing market solutions to identify competitive features for the new product. Our team conducted technical benchmarking, determined key design parameters, risks, development stages, and acceptance criteria. After outlining the work plan and organizing the team, we began designing the layout and electronic schematic for the system. Electronic components and modules were selected, library components were developed, the printed circuit board (PCB) was assembled, and the file for its production was prepared. Subsequently, prototypes were built, and a cloud service was set up for data extraction regarding the system's status. Our mechanical engineers developed the 1.0 concept, prepared a 3D model, conducted fluid and air flow simulations, identified the optimal cooling substance, and prepared the engineering documentation for the first prototype's manufacture.

Initially, we decided to use an off-the-shelf refrigeration solution to expedite development. However, it had a critical flaw for this situation—the lack of a refrigerant charging capability, which posed a significant problem for air transport. Our goal was to enable the Customer to charge the system independently, and the optimal and only solution was to add a charging port to the standard system. Our engineers performed a detailed analysis of existing refrigeration systems to understand the risks of such modifications, studied the requirements for charging ports to determine the appropriate type, selected a charging port that met safety standards and was easy to use, and ensured compatibility with refrigerant R290. The choice of R290 was justified by its non-toxicity and low compressor outlet temperature (ozone depletion potential ODP = 0, global warming potential GWP = 3). Our team also prepared detailed instructions for the Client on how to charge the system with refrigerant independently.

The operation of the device was initially managed solely through adjusting the fan speed, which complicated achieving an optimal balance of temperature and humidity.

In the first iteration of the system, our team encountered difficulties in regulating the airflow through the desiccant. We increased the airflow through the desiccant to prevent the condenser from overheating, as greater airflow was expected to enhance heat exchange and avoid overheating. However, when the airflow increased, the air did not have sufficient time to cool completely as it passed through the cold radiator. This resulted in moisture failing to condense fully and escaping with the airflow, thereby reducing the system's efficiency.

Conversely, when we decreased the airflow, the air had enough time to cool and moisture condensed effectively. Yet, in this mode, the evaporator overheated because insufficient air passed through it for cooling. This caused the evaporator temperature to rise to critical levels, diminishing the overall performance of the system.

To address this issue, a new design incorporating an adjustable bypass valve was developed, allowing for more precise control of airflow and system temperature. In the new system iteration, we designed a dual-channel airflow system: a main path and a bypass path. The main path directed air through both radiators (hot and cold), ensuring maximum water condensation. The bypass path allowed some air to circumvent the cold radiator, preventing its overheating. This solution involved installing an electrically controlled adjustable damper, enabling the modification of the air volume passing through each radiator. This configuration allowed for precise temperature regulation and efficient system operation under various conditions.

The system is designed to operate in direct sunlight, which adversely affects its efficiency. One part of the system contains a refrigerator where cooling occurs, while another part houses a heat exchanger that must dissipate heat to the environment. In hot outdoor conditions, the temperature gradient between the heat exchanger and the air is reduced, making this setup inefficient.

To partially address this issue, we proposed four configurations of insulation materials (steel, sheet plastic, and foam polyethylene) to insulate the walls of the installation. Given the system's operating principles and the components it uses, we could not leave the foam polyethylene unprotected as it would accumulate moisture. Therefore, we proposed covering this material on both sides with different layers.

1) The external layer was a 1 mm thick white metal panel, followed by a 19 mm insulation layer, and then another 1 mm metal layer.

2) The external layer was an 0.8 mm thick white metal panel, followed by a 20 mm air cushion, a 3 mm high-density polyethylene (HDPE) layer, a 5 mm insulation layer, and a 1 mm stainless steel layer.

3) The external layer was a 3 mm black HDPE layer, followed by a 5 mm insulation layer, and a 1 mm stainless steel panel.

4) The external layer was a 3 mm white HDPE layer, followed by a 5 mm insulation layer, and a 1 mm stainless steel layer.

Simulation results indicated that the best external material for the insulation sandwich was steel painted white (with a heating temperature of no more than 49°C at an external temperature of 45°C), while the best results for foam polyethylene were achieved with a 19 mm thickness as in the first configuration.

We combined elements from the first and fourth configurations and integrated this solution into the prototype.

We developed a more complex and adaptive airflow management system to ensure the efficient operation of the installation under various temperature conditions. By adding a bypass path and enabling damper control, we prevented the cold radiator from overheating and achieved a condensation rate of 10 liters per day under standard conditions, without using MOF sorbents. By regulating the direction of the airflows and mixing them, we could utilize standard off-the-shelf components for operation in harsh conditions.