Food Dehydrator Airflow Design

About the project

Project objective: We are developing a food dehydrator. Our first priority is achieving uniform airflow across all 21 trays and across the usable area of each tray. This assignment focuses on designing an airflow prototype that can be tested at room temperature before integrating heating or a heat-pump system. Scope of work - Agree on chamber dimensions, tray spacing, airflow direction, and target velocity. - Develop and compare practical supply-plenum, return-plenum, and tray-channel arrangements. - Assess features such as tapered plenums, guide vanes, perforated plates, baffles, and adjustable balancing openings. - Account for airflow resistance from both empty trays and food-loaded trays. - Estimate total airflow, pressure losses, and the required blower operating point. - Evaluate the recommended concept using engineering calculations and CFD. - Propose a low-cost prototype with adjustable features for airflow balancing. **Key performance requirements** The design should address: - Flow variation between the bottom, middle, and top trays. - Velocity variation across each tray’s usable drying area. - Dead zones, bypass flow, and excessive local velocities. - Sensitivity to changes in food loading and partial tray occupancy. - Blower power and pressure-drop tradeoffs. The target velocity and acceptable uniformity limits will be agreed at kickoff. Please propose measurable acceptance criteria and explain how they will be verified. **Required deliverables** 1. Comparison of two or three airflow concepts, with a recommended design. 2. Dimensioned concept drawings and an editable 3D model. 3. Airflow and pressure-loss calculations with preliminary blower selection. 4. CFD results showing tray-by-tray airflow, velocity distribution, and pressure distribution. 5. Assessment of empty-tray and representative loaded-tray conditions, with assumptions clearly stated. 6. Prototype construction details for plenums, baffles, openings, and adjustment features. 7. A physical test plan specifying measurement locations, instruments, and uniformity calculations. Preferred experience Experience in industrial dryer airflow, HVAC distribution, plenum design, fan selection, and CFD. Practical experience correlating simulations with airflow measurements is strongly preferred. Project boundaries This first phase covers the drying chamber, trays, plenums, and blower airflow system. Refrigeration, heating, and drying-process development will be handled in subsequent phases. **Ownership and communication expectations** We need a self-driven freelancer who can independently take ownership of the assignment, plan the work, identify missing inputs early, and progress without repeated reminders or follow-up from us. The freelancer is expected to: - Proactively recommend design options and explain the tradeoffs. - Provide a brief progress update twice a week covering completed work, preliminary results, next steps, and any blockers. - Share drawings, calculations, and CFD results as milestones are completed. - Highlight issues promptly, along with proposed solutions and any decisions required from us. - Maintain an updated results summary showing airflow uniformity, pressure drop, and blower requirements for each design iteration. - Deliver the agreed work within the committed timeline and coordinate design reviews proactively.

Skills required