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DESIGN AND FABRICATION OF FREEZE DRYER

ABSTRACT

This study explores the advancements and applications of freeze-drying technology, focusing on process optimization, equipment design, and the integration of nanotechnology. Freeze drying, known for its effectiveness in preserving sensitive materials, is increasingly employed in the food and pharmaceutical industries. This research emphasizes recent developments that enhance the efficiency and quality of freeze-dried products while minimizing environmental impact. Key findings indicate that process optimization through machine learning algorithms significantly improves drying cycles by allowing real-time adjustments to temperature and pressure, leading to reduced drying times and enhanced product quality. Additionally, innovative equipment designs, such as microwave-assisted freeze drying, have shown promising results in accelerating the drying process without compromising the integrity of the materials. The study also highlights the critical role of nanotechnology in improving the stability and rehydration properties of freeze-dried products, particularly in pharmaceuticals and nutraceuticals. Furthermore, the integration of freeze drying with other preservation methods, such as supercritical fluid extraction, has emerged as a promising approach for developing high-value products. Sustainability initiatives are also crucial, with findings demonstrating that energy recovery systems and eco-friendly practices can significantly reduce the carbon footprint of freeze-drying operations. Overall, this research underscores the importance of continuous innovation in freeze-drying technology to enhance product quality, operational efficiency, and sustainability in food and pharmaceutical production.

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

The term lyophilization describes one of the modern methods for drying products, including water, food, and human and animal health products (Nowak & Jakubczyk, 2020) (Nowak & Jakubczyk, 2020). Initially, freeze-drying was performed for food drying, and the first industrial application dates back to 1928. Subsequently, the method was intended for the production of injectables (Santana et al., 2022). The first freeze-dried vaccine dates back to World War II. The freeze-dried product is lighter than the same product dried by heating and has a longer shelf life. The freeze-dried products should be protected from moisture. This can be achieved by packing the freeze-dried food in a bag close to the vacuum or by packing it in a bag containing replaceable gases. After that, the package is hermetically sealed (Benyathiar et al.2022).

Freeze dryers are essential for farmers when they want to keep their products for various reasons while maintaining the quality and high prices of the products (Delgado et al., 2021). In addition to farmers, freeze dryers are also needed by other industries that require freeze-dried items, such as pharmaceuticals, health products, and biotechnology. The system is divided into three parts: namely, the condenser, vacuum pump, and benton (Awofiranye, 2020). The lateral fridge freeze dryer, including prevention or important gravity, can be disturbed by the position of important pipes. The parameters that significantly influence the drying conditions are temperature, pressure, air input speed, and sample thickness. A freeze dryer with a hot gas defrosting method can reach a final vacuum of 0.0391 hPa. In freeze dryer performance testing, the process is divided into five stages, beginning with the operation of the condenser and vacuum pump. The average storage ability is tested in excess of 24 hours after a harsh working process (Gao et al.2022).

The term "freeze drying" is widely known as lyophilization. Freeze drying is a low-temperature drying process where the product is frozen. After the product is frozen, the pressure is reduced below the triple point of the material in an airtight chamber. (Zhu et al.2021) Water and other solvents will sublime directly from the solid phase to gas, while the product is kept at temperatures less than 32 °F, and its structure and properties remain the same as before the process (Liu et al.2022). Placing the sublimation can occur in the form of a porous structure, which was unavailable for the liquid molecules in the solid phase, so that the product can be kept for a longer period of time. In general, contact heat at a given temperature that does not lead to degradation of the product is provided under low pressure. Since the beginning of preservation, drying has been used as a simple and reliable method (Merivaara et al.2021). As an advancement, the development of various drying methods, especially freezing, has been further improved to meet the demand of various industries. Freeze-dried or lyophilized products generally provide superior quality compared to other drying methods, especially in the field of flavors, including food, and in the field of remedies related to the medical world. For long-term storage, the best storage method would be freeze drying; this method is better in comparison to spray drying and traditional drying because the product can be stored for at least a year and does not need to be ground before application. However, a large freeze drying machine has some drawbacks, especially due to the powerful pump usage, which may require a large amount of electricity (Orrù et al.2020).

1.2 Problem Statement

The freeze dryer system requires separate units for condensation and sublimation. The existing units are indirectly cooled models using refrigeration units (Authelin et al.2024). The refrigerant-based cooling does not work continuously for 24 hours a day because of the cleaning required for a smooth process. In addition, if the vacuum pump gets filled with condensed water, the condensation capacity of the sublimation units is insufficient to handle it. The multiple condensation points and their cleaning not only consume high costs for cooling water and vacuum pump oil but also incur high operational costs for condenser cooling. For such a system or allied system, the energy dampers are much higher (Singh, 2023).

To avoid the above problems, instead of a condensation chiller, a sublimation chiller can be used with water-based cooling. The performance of the freeze dryer has to be improved to maintain market demand. The end product quality should be uniform, like skin dosage and volume expansion. A single unit should be able to serve both purposes indoors. Automated loading and unloading may improve the requirements. Thus, these are the main tasks to be achieved through the design and fabrication of the freeze dryer system. To address the above issues, the proposed design and fabrication of the freeze dryer unit should be designed for outdoor ambient temperatures and 24 hours of minimum performance. Even though water cooling can be used, it should be indirect and not a direct utility user (Ascione et al., 2020). The operation and regular maintenance should be easy. The equipment should be capable of handling large tuber crop slices or cubes. The skin dosage of the lyophilized mushroom slice should be more than 45 ± 5. The volume expansion ratio of the lyophilized garlic slices should be more than 20 ± 5. The above requirements are essential to satisfy the consumer and the establishment. Hence, to accomplish the market requirements, the aim is to propose the design and fabrication of the freeze dryer.

1.3 Aim and Objectives

Aim:
To design and fabricate a functional and efficient freeze dryer suitable for preserving perishable materials by removing moisture content through sublimation.

Objectives:

1.  To design an electrical control system for the freeze dryer that ensures precise temperature and pressure regulation.

2.  To fabricate a freeze dryer with optimal components and materials that support efficient moisture removal while maintaining the integrity of the product.

3.  To test and evaluate the performance of the freeze dryer in terms of drying time, energy consumption, and product quality.

4.  To compare the performance of the fabricated freeze dryer with existing commercial models to assess improvements and limitations.

1.4 Significance of the Study

The design and fabrication of a freeze dryer are of great significance in various industries, including pharmaceuticals, food processing, and biological research. Freeze drying is essential for preserving perishable materials while maintaining their structural integrity, flavor, and nutritional value. This study provides a cost-effective solution for developing a freeze dryer that can be applied in smaller-scale operations, enabling wider accessibility to efficient preservation methods, particularly in developing regions where advanced technology may not be readily available. By understanding the underlying principles of freeze drying and constructing a model, this project contributes to the knowledge pool in the electrical and mechanical design of preservation systems.

Additionally, this study will benefit academic institutions, small-scale businesses, and research facilities by providing a blueprint for developing low-cost, energy-efficient freeze dryers. It will also promote local manufacturing capabilities and reduce dependency on imported equipment. Furthermore, the results of this research can inspire further innovations in drying technology, with potential applications in medicine, agriculture, and other sectors where long-term preservation of products is critical.

1.5 Scope of the Study

This project focuses on the design and fabrication of a functional freeze dryer, targeting small-scale applications in the food and pharmaceutical industries. The scope includes the electrical and mechanical design aspects of the system, starting from component selection, circuit design, and material selection, to the actual fabrication process. The study will also cover the testing and validation of the fabricated freeze dryer to ensure it meets specific performance metrics, such as moisture removal efficiency, drying time, and energy consumption.

However, the project will not cover the large-scale industrial freeze dryers that are more complex and expensive. The system designed and fabricated in this study will be limited to a prototype model, with possible scaling options in the future. The focus will be on a basic freeze dryer system, which includes components such as a refrigeration unit, vacuum pump, and heating system. The freeze dryer’s performance will be tested on selected materials to assess its efficiency, but full commercialization and mass production are beyond the scope of this project.

1.6 Limitations of the Study

One limitation of this study is the constrained availability of advanced materials and components, which may affect the overall performance and efficiency of the freeze dryer. Due to budgetary and resource constraints, the system designed in this study may not achieve the same level of performance as commercially available freeze dryers. The fabrication process will rely on readily available materials, and as such, some compromises may be made in terms of durability and functionality, which could affect the overall lifespan of the freeze dryer.

Another limitation is the scale of the system. This study focuses on a prototype freeze dryer for small-scale applications, and its performance in larger-scale operations is not explored. Additionally, the testing phase will be limited to a specific range of materials, which means that the freeze dryer’s versatility across different types of products may not be fully assessed. Finally, the system’s energy consumption may not be optimized, given the limitations in the available power systems and the complexity of fine-tuning temperature and vacuum controls at a larger scale.

1.7 Definition of Terms

Freeze Drying (Lyophilization): A dehydration process used to preserve perishable materials by freezing them and then reducing the surrounding pressure to allow the frozen water to sublimate directly from solid to gas.

Sublimation: The process by which a solid changes directly into a gas without passing through the liquid phase, a key principle in freeze drying.

Vacuum Pump: A device that removes air and reduces pressure inside the freeze dryer chamber, facilitating the sublimation process during freeze drying.

Refrigeration Unit: A component of the freeze dryer responsible for lowering the temperature to freeze the material before the drying process begins.

Condensor: A part of the freeze dryer that collects water vapor by condensing it after sublimation, turning it back into ice.

Heat Transfer: The process of transferring heat energy to the frozen product in the freeze dryer to facilitate sublimation.

Product Chamber: The section of the freeze dryer where the material to be freeze dried is placed, subjected to freezing and vacuum conditions.

Moisture Content: The amount of water present in a material, which is removed during the freeze drying process to preserve the product.