Performance Optimization of a Passive Heating Solar Fruit Dryer

Project Title

Performance Optimization of a Passive Heating Solar Fruit Dryer

Project Area of Specialization Mechanical EngineeringProject Summary

Increasing global population entails increasing food production. While improving productivity is key, reducing the existing high rates of global food loss and waste, including post-harvest loss, along the various production and supply chains, as post-harvest losses as high as 30-40% in both industrialized and developing countries. Inappropriate and sub-optimal drying practices along the food value chain have led to significant income losses among farmers, food distributors, processors, and exporters. In this regard, the use of appropriate drying technologies can potentially enable small-scale producers to significantly reduce post-harvest losses, improve the quality of food, and generate income and employment opportunities.

The proposed project is suggesting an efficient solution to tackle the problem of food insecurity and farmer economy, as solar drying is capital-intensive method, has negligible costs for fossil fuel and combustion equipment and too short payback period. Thus enables the small-scale producers to significantly reduce post-harvest losses in a cost-effective and energy-efficient manner, improve the quality of food, and generate additional income and employment opportunities. The proposed project increases the market value of product through improved quality, high yield, and less land use and secure stable and high income even under various climatic conditions. The solar dryer proposed is technologically compatible and promises the food quality using controllable drying temperature and air flow rate which is not achievable using traditional methods of solar drying.  It also promotes clean energy. The project involves the mathematical modeling using the thermodynamic relations for the dryer system. In addition, a computational fluid dynamics (CFD) simulation using Fluent was applied to predict the temperature distribution and obtaining the uniform air flow field and uniform heat flux inside the drying chamber .The key features expected to improve the viability of the solar dryer will be analyzed. Temperature and moisture sensors are installed to measure value of various parameters for experimental analysis.

Project Objectives

The primary objectives of the current study, but not limited to, include

• To carry out CFD analysis of solar dryer to achieve uniformity of air flow field inside the drying chamber.
• To optimize the design of solar dryer to obtain higher drying rates.
• Energy and Exergy analysis to obtain and improve the experimental efficiencies of solar dryer.

Recently, a lot of researches are being carried out on related to storage of food. Storage of agricultural products has been an important issue challenged in emerging countries. According to a global report published jointly by FAO, WFP, UNICEF, WHO and IFAD in 2019, 20.3 per cent of Pakistan’s population (40.0 million people) is undernourished/food insecure. Pakistan suffers from a shocking level of hunger as reported by the Global Hunger Index 2020. 40 per cent of food in Pakistan is wasted. This includes food loss during the supply chain (production, processing, retailing, and consumption has detrimental effects on food prices and inflation and ultimately results in hunger.) that occurs every year.

To tackle with the aforementioned challenges several approaches of preserving food have been used in the past. However, the most common among them remains the cold storage. Unfortunately, the method is quite expensive and unaffordable to the farmer. In present era, a lot of methods are being used to preserve food, from which there are some methods in which the minerals of food are not preserved by virtue of some reasons. Open sun drying is a common practice due to its low cost and least effort. However, there is loss of minerals in stored food is harmful rays which are emitted by sun. Moreover, open sun drying compromises on colour, flavour and involves dust and other undesired factors in to the stored food. Passive Drying vegetables and fruits with thermal energy enables longer storage times and easier transportation. The product is protected against flies, pests, rain and dust. A novel design based on solar drying with forced heating is proposed in the current research. It is also economic, environmentally friendly and labour saving. The product can be left in the dryer overnight or during rain and is thus not labour intensive either. The quality of the product is better in terms of nutrients, hygiene and colour.

• Food wastage/ loss.
• Sustainable management and utilization of natural resources.
• Enhance quality of life for farm families.
• Food security.
• Hunger people.

Project Implementation Method

Methodology

• CAD Modelling using Solidworks

The fruit dryer was modeled in solid works. The dryer consists of the parts like drying chamber, plenum chamber, air duct and trays are arranged vertically inside the dryer are modeled and assembled as per the dimensions.

• Mathematical Modelling

The set of mathematical equations for moisture content, thermal efficiency of solar collector, theoretical and experimental efficiency of drying chamber, exergy inflow and outflow, exergy efficiency, exergy improvement potential  are solved by numerical simulation. A simplified mathematical model for the solar dryer is developed to analyze designs.

 Energy and Exergy Efficiencies

To perform experiment and carry out energy and exergy analyses and evaluate the efficiency of the solar dryer.

• CFD Analysis

Thermodynamic simulations of the drying chamber are performed. In addition, a computational fluid dynamics (CFD) simulation of the air temperature and velocity inside the drying chamber is performed. The key features are expected to improve the viability of the solar dryer. To perform CFD analysis and observe fluid flow behavior and make changes to obtain uniform heat flux.

• Fabrication

The optimized design of solar dryer will be fabricated for Experimental evaluation of obtained results from CFD simulation and to perform analysis for various products to study drying characteristics.

• Installation of experimental platform

Experimental Test

Presentation, submission and publication of results

Benefits of the Project

Some of the most significant benefits of solar dryers are discussed as follows:

• Avoid wastage of crops and dried products will bring monetary benefits to farmers.
• It strengthens farmers' bargaining position. Because they can't store or keep their surplus crops, farmers can sell at relatively low rates during the harvest season.
• The quality of dried food is better.
• Due to high temperature in the drying chamber, the drying duration of product is less.
• Food is prevented from insects.
• Food is not exposed to moisture during rainy season, and dust etc.

The dryer can be used all around the year for different crops such as it can be used to dry spices like chilies, coriander, pepper, and turmeric, as well as dehydrating fruits and vegetables like mango, grapes, banana, carrot, potato, and many others. It is also very useful in drying herbs that need to be protected from direct sunlight. Medicinal plants use benefit from the sun dryer. Solar dryers not only assist to reduce fuel use and pollution, but they also increase the quality of the final product.

• Dried fruit can be eaten as a snack or used in stews, soups, and casseroles. It can also be used to make ice cream and baked goods, as well as cereals for breakfast.
• Individuals are encouraged to start their own gardens.
• Drying takes less time because the dryer is warmer than the outside.
• Because of the speed with which the food is dried, there is a lower chance of deterioration. (If the drying process is too slow, the fruit will ferment and destroy the product.)
• The item is resistant to insects, bugs, rain, and dust.
• It saves time and effort.
• The product's quality is improved in terms of nutrition, hygiene, and color when kept in the dryer overnight or during rain.

Professional drying techniques can be used in solar drying to meet the genuine needs of huge agricultural productions while also ensuring product quality and consistency. A solar batch convection dryer designed along these lines is given, and its efficacy in drying fruits and vegetables, as well as the methodologies employed to dry these goods, is addressed. The drying of materials is an important and necessary mechanism in the manufacturing process. Fruit and vegetable drying is a time-honored method of food preservation.

Technical Details of Final Deliverable

The efficiency of presented model of Passive Heating Solar Food Dryer (PHSFD) shall be more than other traditional solar dryers owing to novel geometry, use of intake blower powered by Solar PV. Moreover, to examine its efficiency because it is completely based on CAD Modelling using solid works, Mathematical Modelling, Energy and Exergy Efficiencies and CFD Analysis were carried out. The Passive heating solar food drier shall be more beneficial as compared to active heating Solar Food Dryer because in active solar food drier (open sun drying), the chance of losses of nutrients, loss of taste, color and quality is more as compared to passive heating solar food dryer.

The capacity of storage will be also be higher because of the increased useful space containing products to be dried. There will be a homogeneity in the drying rate of products due to cylindrical design. In the cylindrical design there are very less chances of losses as compared to the triangular or rectangular shaped design. The role of ducts is much important and they are designed in a manner in order to increase the efficiency by providing a common drying rate with a uniform air flow. The blower being used shall increase the air flow rate and because of the cylindrical shape and equidistance of the ducts from each other in a triangular way, it will become much efficient.   

Final Deliverable of the Project Hardware SystemCore Industry FoodOther Industries Agriculture , Energy Core Technology Clean TechOther TechnologiesSustainable Development Goals No Poverty, Zero Hunger, Good Health and Well-Being for PeopleRequired Resources

Item Name	Type	No. of Units	Per Unit Cost (in Rs)	Total (in Rs)
			Total in (Rs)	78750
Centrifugal blower	Equipment	1	6700	6700
Solar Collector	Equipment	1	5500	5500
PVC Pipe	Equipment	2	1250	2500
Body Structure (Including 3 steel duct and 3 drying tray)	Equipment	1	27500	27500
Heat Absorber Element	Equipment	1	7750	7750
Sensor (Temperature & Moisture)	Equipment	3	2000	6000
Fabrication	Equipment	1	13500	13500
Printing	Miscellaneous	10	350	3500
Travel cost	Miscellaneous	2	500	1000
Labour cost	Miscellaneous	6	800	4800