Development of a Low-Cost Soil Drying Oven

Soil drying ovens are used by civil engineers to test suitability of ground conditions for roading and construction projects. These ovens are required to meet the industry standard NZS 4402: 1986 – Methods for testing soils for civil engineering purposes. Commercially available ovens can be expensive. Hence, this project investigates the in-house design of a low-cost soil drying oven. The main specifications of the oven required a capacity of 250-500 L, single phase 230 V AC supply, and temperature regulation between 105°C and 110°C with a readable accuracy of 1°C. Major influencing factors included: low-cost, locally available (NZ) parts, and easy assembly and portability.

Engineering students from mechanical and electrical disciplines have worked in two teams to develop solutions. Both teams utilised Arduino microcontrollers to implement PID temperature regulation. The teams had variations in the number of heating elements and temperature sensors used in their designs. Other electrical control features implemented included a setpoint potentiometer, LED indicators and an LCD display. For the mechanical design, the teams utilised an angle iron frame with stainless-steel sheet metal. Glass wool insulation was used between the exterior and interior cavity to increase thermal insulation. Integrated removable trays were designed to house the electrical control system.

The estimated total cost for materials was approximately $900 for one group and $1200 for the other group. The oven has not been fully fabricated yet due to CoVID-19. However, parts of the design have been tested functional in simulations. Future work will include fully constructing the ovens and testing them in the lab.

Fig. 1: Mechanical Design

Fig. 2: Electrical Design

TENCON 2021 Presentation

For more details on this project refer to the following:

Conference Papers:

1. Chand, P., Foulkes, M., and Kumar, A. Towards the Development of a Low-Cost Soil Drying Oven.​ The 2021 IEEE Region 10 Conference (TENCON), 2021, Auckland, New Zealand. 10.1109/TENCON54134.2021.9707453

2. Chand, P., Foulkes, M. and Kumar, A. (2022) Design of a low-cost soil drying oven. Manufacturing, Design, Entrepreneurship (MaDE) 2022, 2022, Auckland, New Zealand.