Tec de Monterrey, 2022

A 2 FOR 1 DEAL

The project took place at Leche Delicias, a dairy company, where the team’s challenge was to analyze the plant’s industrial chiller system and explore ways to use its waste heat to improve overall energy efficiency. The idea was to move beyond simply cooling milk and transform the chiller into a co-generation system, extracting value from every joule of energy involved in the process.​

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The first step was to understand the machine thoroughly. The team conducted an on-site visit, studying the four-part refrigeration cycle: compressors, condensers, expansion valve, and evaporators. They characterized the working fluids, R-410A refrigerant, water, oil, and milk, and their thermodynamic properties, including specific heats and phase-change temperatures.

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The objective was clear: quantify the mass flow and heat loss of the chiller and propose solutions that reduce waste heat or reuse it elsewhere. The team hypothesized that, because the machine was well-insulated and designed for efficiency, heat losses would be minimal/likely too small to power anything significant, such as a motor.

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Using operational data (pressures, temperatures, mass flow rates), the team performed a complete energy balance of the refrigeration cycle. They interpolated enthalpy and entropy values from R-410A property tables for each state point in the cycle, calculating energy input, heat rejection, and overall system efficiency. The result was striking: only 0.039 kW of recoverable heat was escaping from the system; less than the energy needed to power a single light bulb. This confirmed that the chiller was already operating very efficiently, with negligible thermal waste available for reuse.

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Even though the available heat was minimal, the team designed a conceptual solution to capture it. Their proposal involved installing a hood (“campana”) over the chiller fans, ducting the hot air through a narrowed neck to increase velocity, and channeling it through a small vertical-axis turbine to generate electricity. The air would then pass through passive radiators to cool before being reintroduced into the system’s intake.

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This concept was modeled in SolidWorks, including the chiller geometry, ducts, turbine, and radiator. The design was then tested using ANSYS simulations, which confirmed that the hood shape successfully concentrated the airflow enough to rotate the turbine, albeit with limited power output. The team emphasized that, in a real-world application, a circular duct design could further improve efficiency.

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Recognizing that materials would significantly affect heat retention and cost, the team compared galvanized steel and stainless steel 304 as candidates for the hood. Galvanized steel emerged as the optimal choice: it provided corrosion resistance, sufficient structural integrity, and cost-effectiveness (≈6.2× cheaper than stainless steel).

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For the turbine, aluminum was chosen for its light weight and ease of forming, keeping the material cost around 112 MXN. Overall, the proposed system’s cost was within a range suitable for small-scale implementation, though its energy yield was too low to justify large-scale investment.

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Since thermal recovery potential was limited, the team broadened the scope and suggested non-mechanical improvements for overall operational efficiency and milk quality:

• Thermal insulation optimization – using thicker insulation (up to 2") on fluid lines to minimize energy losses.

• Improved cow welfare practices – automating stall cleaning to prevent mastitis, monitoring stray voltages in barns to reduce stress, providing scratching posts and enrichment to increase serotonin (and milk calcium content), and monitoring somatic cell counts to maintain herd health.

These recommendations reflected a systems-thinking approach, addressing efficiency not just at the machine level but across the entire production process.

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The project confirmed that the chiller was already close to thermodynamic ideal efficiency, leaving very little heat to recover. Nevertheless, the study showcased the value of combining thermodynamic analysis, 3D CAD modeling, and simulation to validate a concept and deliver practical, budget-conscious recommendations. By thinking beyond machinery; considering animal welfare, preventive maintenance, and process optimization, the team demonstrated an engineering mindset that balances technical rigor with operational impact.

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Please find attached below the relevant documents to this project. (Note: most, if not all documents, are in Spanish)