Designing Greenhouse Dryers for Seaweeds

Project Info

Case

We were requested by one of our clients for designing two adjacent chambers for drying seaweed. This plant is used as a desirable source of food for some countries in Southeast Asia. Aside from their beneficial nutritional properties, Seaweeds are also harvested or cultivated for such applications as the extraction of polysaccharides. Such substances are especially used in food industries as food additives. They are also used for cancer prevention regimes.

The client requested us the calculation and designing chambers that were to be used for the in-house growing of seaweeds.

Requirement

  1. The design had to be cost-effective with the lowest production cost.
  2. The design had to effectively prevent any loss of heat
  3. The design had to comply the environmental conditions of the given location

Solution

In order to implement a cost-effective solution, a comprehensive work was done for finding a solution for improving a forced convection for the requested greenhouse dryer design in the given location. The work included calculations of air flow rate, fan, and supplementary heater requirements. This idea was further developed and proper thermal calculations were made to provide the design details for the facility that was composed of two 10 x 10m rooms. In order to make sure that the design complied the environmental condition of the point, necessary information regarding the location of the greenhouse was gathered. Below includes some or the data that were used in the analysis

  1. The greenhouse dryer (double chamber dryer) was placed in Chile, South America.
  2. The average daily solar radiation at this point is 6kWh/m2.
  3. The average ambient temperature during the day is 30-34 oC, with relative humidity RH=70-80%.
  4. The average ambient temperature during the night is 26-30 oC, with relative humidity RH=70-90%.
  5. The required temperature inside greenhouse dryer is 50 o
  6. During the day (on sunny days) the required temperature is achieved without supplementary heating.
  7. During the night and on cloudy days the required temperature is achieved with supplementary heating (biomass boiler).

Based on the work, the design team designed both rooms in a way that once one of them was emptied, its thermal energy was pumped into the other room.

The core of this system was to reverse the direction spin of fans to change the airway in the duct connecting the two rooms. This way, the warm air in one room was automatically sent to the other room.

This helped using an already warm air for the other room, and therefore, saving the existing thermal energy without the need of using electrical energy to heat the other room.

Description

The final design met all the given requirements. The solution provided an efficient yet simple solution that could be easily made. Based on the given solution, this workshop was finally built and is currently working.

Client:
K. Alvarez
Date:
April 13, 2018
Location:
Chile
Category:
Mechanical Engineering