Thermodynamic Analysis of Milk Pastueraization System using Flat Plate Solar Collector

Thermodynamic Analysis of Milk Pastueraization System using Flat Plate Solar Collector

Salem Alabd, Mohd Shahid, Abdulbasit Mansour, Masroof Ahamad

Higher Institute of Engineering Technology, Tripoli, Libya Satya College of Engineering, Haryana, India.

University polytechnic Jamia Millia Islamia Central University New Delhi, India

Abstract currently more than 50% of all milk produced in world is processed. The world dairy industry has long relied on non-renewable energy sources, which are not only becoming more and more expensive but are also to blame for major health issues and environmental issues including global warming. As a result, the all governments, social and environmental organizations and scientific communities have all pushed for the adoption of green energies. Solar energy has emerged as the most promising among the green and renewable energies.

The pasteurization of milk requires a significant amount of conventional energy, which is reduced when solar energy is used instead. Therefore, using solar collectors at the different angles =+15, ß=, =-15 calculate the amount of energy intensity and temperature of output water. Additionally, determine the quantity of collectors needed to heat milk to pasteurization temperature.

Keywords Milk pasteurization Temperature, Energy intensity, Solar Flat Plate Collector

Nomenclature:

INTRODUCTION

India is one of the dairy-producing countries with the quickest growth rates. Demand for dairy and food products is rising daily as a result of population growth and improvements in lifestyle. In the past 20 years, commercial energy consumption has climbed 6% in tandem with rising product demand, placing India fifth globally in terms of total energy consumption. Approximately 49% of all energy usage is in the industrial sector. Currently, natural gas is imported 31% of the time, crude oil 77% of the time, and coal 9% of the time [1]. The solar constant, or 1353 W/m2, is the amount of solar energy that passes through the earth's atmosphere per second. Of this, the atmosphere absorbs over 190 W/m2. Direct radiation and dispersed radiation make up the remainder. A total of 473 W/m2 of direct and scattered radiation is absorbed by the earth and can be used for a variety of purposes. Only around 383 W/m2 of this energy is reflected back to space by clouds. Since the implementation of the ninth plan, the Indian dairy industry has experienced significant expansion. India is the top milk- producing country in the world as a result, producing 127.9 million tonnes of milk annually in 201112 (and an anticipated 140 million tonnes in 201314) [2]. This indicates a consistent increase in the supply of milk and dairy products for our expanding population. Most milk production in India takes place in rural regions. Evidently, it can be a reliable source of money if handled and processed appropriately [3].

Milk and milk products are put through a number of unit processes in dairy processing plants, including filtering, clarifying, homogenization, pasteurization, sterilization (UHT treatment), cooling, packaging, and refrigeration. For the manufacture of UHT milk, powder, cheese, butter and liquid milk pasteurization, the corresponding steam pressures are 1.5, 2.2, 3, 3 and 10 bar [4]. Currently, liquid milk accounts for about 49% of the nation's total milk production. Around 26.5% of the whole milk is transformed into ghee, 7% into curd, and 6% into butter out of the remaining 51%. The remaining 11.5% of the milk is used to make other dairy products including ice cream, paneer, and khoa. Conduction, conduction-convection, and radiation are some of the ways that heat energy is transported in industrial processes. Electric resistance heaters use conduction to transfer heat energy. Furnaces and radiant heat dryers use radiation. In many processes, the equipment functions cyclically, as in regenerative furnaces and agitated process vessels, but frequently it does so in steady-state settings. Traditionally, fossil fuels (coal, petrol, diesel, etc.) are used to generate heat to produce steam/hot water, which is then used as a heating medium in PHE [5]. The combustion of these fossil fuels contributes to pollution as well as greenhouse gases

(GHGs) [6], which contribute to global warming. Furthermore, these energy sources are non-renewable [7].

According to Li et al. [8], SWHs typically consist of solar collectors and a storage area. It operates on the principle of the thermosyphon or the disparity in density between hot and cold water. To satisfy the requirements for an acceptable pasteurisation, Nielsen and Pedersen [9] developed a milk pasteurisation system based on solar panels. They discovered that the solar panel provided a maximum temperature of hot water of about 100C through absorption of solar energy, which was successfully used for pasteurising milk. Water heating is one of the easiest, most affordable, and least expensive uses of solar heat, according to Agbo and Oparaku [10]. The price of heating 100 litres of water with a solar hot water system was compared by Philip [11, 12].

The pasteurisation procedure is crucial for industries, according to the literature assessment. It will benefit the environment if milk is pasteurised using solar energy. Therefore, one of the main goals of this research is to analyse solar-powered pasteurisation systems and determine the bare minimum number of collectors needed to pasteurise temperature.

Fig. 1. Diagram of Solar Collector Milk Pasteurization System (SCMPS)

METHODOLOGY:

1. The solar energy is utilised in flat plate collector to produce hot water. The flow rate of water is determined by using following formula.

   Heat given by hot water = heat taken by milk mw cpw T = mm cpm ( Tpm Tin)

   The overall analysis of the system has been done the analysis of Flat Plate Collector (FPC) was carried out, wherein the results obtained from the first phase were utilized. The rate of

   useful energy gain () delivered by the solar flat plate collector is given by eq. (1):

   (1)

   In other terms, Eq. (3.2), can be rewritten as:

   (2)

   (3)

   The amount of solar flux absorbed by the absorber plate is given by Eq. (3):

   The instantaneous efficiency of the collector is given Eq. (4):

   (4)

   where is represents the heat removal factor of the collector and it is given by:

   (5)

   In Eq. (6), F represents the efficiency factor of the collector.

   (6)

   he hourly solar radiation falling on the tilted collector surface is given by Eq. (7):

   (6)

   The tilt factor for the beam radiation is given by following Eq. (8):

   (7)

   where, is the declination angle whose expression is given in Eq. (9):

   (8)

   The time used for calculating the hour angle is the local apparent time and it can be calculated using the relationship given in Eq. (10).

   Local Apparent Time = Standard time ± 4 (Standard time longitudelongitude of location) + (Equation of time correction)

   (9)

   The time correction (in minutes) can also be calculated from the following empirical relation:

   (10)

   where B = and is the day of year.

2. The outlet temperature of hot water coming from the collector is determined and it has been seen either this temperature is sufficient to pasteurize milk or not.

3. Initially we use one collector, if it is not available to give sufficient temperature to pasteurize the milk the number of collector will increase.

In this way we will determine the no. of collector required to supply hot water of required temperature.

RESULT

The amount of solar energy incident on a surface is depending on angle of incidence. For the given system the amount of solar energy calculated for the different angles. In the months of summer, at an angle =+15, the amount of solar energy available is 806.12 Wh/m2 and at an angle equal to =, the amount of solar energy is 887.36 Wh/m2. For the angle of = -15, solar energy available is 925 Wh/m2. Hence the amount of solar energy available is increases as we move from = +15 to = -15.

For the utilization of solar energy there is use of solar flat plate collectors. Number of solar collectors used is depends upon the

temperature required for the pasteurization. For the given system temperature of water required is 96.8C, so for achieving the temperature use number of collectors as shown in Figure 2 and the number of Flat plate collector for this study related to months and location as shown in table 2. The maximum energy available at 12.5 ST is 887.36 Wh/m2 for the month of May, and lowest in a day at 16.5 ST. presented in table 1.

TABLE I: Incident Radiation for the different month.

TABLE II: Number of collectors required for the different month

Fig. 2. Number of solar collectors require to achieve outlet temperature.

Since MATLAB is a highly powerful technical language software for mathematical programming (Shailendra Jain [13]. MATLAB 17a was used to solve the mathematical expressions of the SFPC. The results so obtained for the SFPC have been provided in the present subsection. The location was selected from Libya to carry out the study and this was: Tripoli (32 º 8877N, 13 1872ºE). The input data for the analysis were collected on 15th May. The initial conditions that were considered for the analysis is listed in Table 3 were use.

TABLE III: Performance of FPC for the whole day on 15 of May in Tripoli

CONCLUSION:

Libya has enough of sunlight virtually all year round because it is located in Mediterranean climate a hot, very dry summers and warm winters. Utilising this enormous amount of energy,

which would otherwise be lost, for beneficial activities would not only protect the environment but also benefit business owners financially. Dairy businesses can use solar water heating systems to process raw materials and create finished goods. It has been used in the dairy sector for pasteurisation, sterilisation, preheating, and the production of paneer, among other things. Given the current situation, the same can be adopted for additional processing units as well as other dairy and food processing factories.

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