Solar Powered Thermoelectric Air Conditioning for Temperature Control in Poultry Incubators

Abstract

Proper air conditioning is crucial for hatching, growing, and reproducing poultry chickens. The existing methods are often costly and only viable for some chicken farmers. This paper presents a novel solar-powered thermoelectric module that utilizes the Peltier effect for efficient cooling and heating in poultry incubators. The proposed system consists of a Peltier module with cool and hot junctions, powered by a solar panel through a charge controller and battery. The cool junction is located in the chicken-breeding and reproduction unit, while the hot junction is situated in the egg-incubation unit. Temperature controllers maintain the required temperatures of 35–40 °C for the egg-hatching and 10–24 °C for the chicken-growing units. The experimental results demonstrate the system’s effectiveness in maintaining the desired temperatures. This solar-powered thermoelectric air conditioning system offers advantages over traditional methods, including lower energy consumption, reduced costs, and eco-friendliness. It has the potential to benefit off-grid poultry farmers and reduce energy bills for existing chicken farms. The mathematical modeling, load calculations, and prototype results show that the proposed system is best suited for providing the required cooling and heating effects in poultry incubators. This research represents a significant step forward in temperature control for poultry incubators and could revolutionize poultry farming practices, especially in remote locations with limited electricity access.

1. Introduction

Thermoelectric modules convert heat energy into electrical energy and vice versa. The temperature difference between the hot and cold junctions creates a potential difference, which generates electrical energy [1]. The generated electrical energy, in turn, creates a temperature difference between the two junctions, where the cold junction becomes colder, and the hot junction becomes hotter [2]. These modules are primarily used for cooling and heating applications. The Peltier effect explains the phenomenon of temperature difference when an electrical supply is applied, while the Thomson effect describes the direction of the current. The Seebeck effect explains the generation of electricity by maintaining hot and cold junctions using conductors or semiconductors [3].

Thermoelectric modules offer an attractive solution for heating and cooling applications because they can simultaneously produce both effects when supplied with direct current (DC) [1,2,3,4]. Additionally, they can generate electricity through the Seebeck effect [1,2,3,4]. The poultry industry faces numerous challenges related to egg hatching, chicken growth, and reproduction [5,6,7]. Inadequate air conditioning is one of the primary issues in poultry farms. Chicken egg hatching requires warm temperatures of approximately 40 °C and humidity levels between 50–70%, while chicken growth and reproduction necessitate cooler temperatures, ranging from 10–24 °C [5,8]. Traditionally, fluorescent or incandescent lamps are used for egg hatching, providing sufficient light and heat at different stages of the hatching process [9,10,11,12,13]. However, these lamps consume significant amounts of electrical energy and are prone to frequent failures, making them less reliable [14,15,16,17,18].

Research on off-grid solar-powered thermoelectric air conditioning systems for poultry farms has been growing, addressing the critical need for sustainable temperature control solutions [5]. Studies emphasize the importance of maintaining optimal temperatures for poultry health and productivity, highlighting the limitations of conventional cooling methods and the potential of solar-powered thermoelectric systems to offer reliable off-grid solutions [19]. Recent advancements focus on enhancing system efficiency, durability, and cost-effectiveness through innovative approaches such as improved heat exchanger designs, advanced materials for thermoelectric modules, and the integration of smart control technologies [20]. Case studies and field trials demonstrate promising results, indicating the feasibility and benefits of deploying such systems in real-world poultry farming environments. However, challenges remain, including cost barriers, technical limitations, and scalability issues, necessitating further research to address these constraints and unlock the full potential of solar-powered thermoelectric air conditioning for sustainable poultry farming practices [21].

For these reasons, a heat-ejecting fan connects the Peltier module’s hot junction to the egg-hatching unit, and hot water is supplied below the egg trays to create humidity. This mechanism consumes less energy and reduces the time required to reach the desired warm temperatures (approximately 40 °C) and humidity levels (50% to 70%) [22]. Furthermore, this method can facilitate faster egg hatching, usually within 21 days [23]. Existing air-cooling systems for chicken-growing and reproduction farms typically use refrigeration gas-based air conditioners or electric fan-based air coolers [24,25,26]. These systems are expensive and consume substantial amounts of electrical energy. To address this issue, the cold side of the Peltier module is connected to the chicken-growing and reproduction unit, which requires temperatures ranging from 10–24 °C [27].

A single Peltier module serves both functions: warming up the egg-hatching unit and cooling down the chicken-growing and reproduction unit. This setup suits both hot and cold weather regions, as the cold and hot junctions can be reversed [28]. Various Peltier modules, also known as thermoelectric coolers (TECs), are available on the market, most of which are primarily used for cooling purposes [29,30,31]. In this research, hot air is ejected into the egg-hatching unit through an exhaust fan. TECs create a heat flux between two different types of devices and are specified by size, power consumption, and temperature range [29,30,31]. They are classified into single-stage, multi-stage, high-temperature, thin-film, and high coefficient of performance (COP) types [32]. For this research, a high-COP TEC module is preferred, since it must perform both effective heating and cooling simultaneously.

Table 1. Comparison of various TEC modules (cold junction).

	Current (at 12 V)	Time to Reach 10 °C	Temperature after 1 h	Temperature after 2 h
TEC1-12705	2.57 A	56 min	5.6 °C	2.9 °C
TEC1-12704	2.73 A	58 min	6.2 °C	6.7 °C
TEC1-12706	3.18 A	59 min	7.3 °C	6.9 °C
TEC1-12703	3.47 A	55 min	5 °C	2.6 °C

and

Table 2. Comparison of various TEC modules (hot junction).

	Current (at 12 V)	Time to Reach 50 °C	Temperature after 1 h	Temperature after 2 h
TEC-12705	2.57 A	54 s	54.6 °C	56.3 °C
TEC-12704	2.73 A	55 s	53.9 °C	55.5 °C
TEC-12706	3.18 A	56 s	52.6 °C	54.7 °C
TEC-12703	3.47 A	45 min	55.3 °C	59.2 °C

present the performance comparison of various high-COP TEC modules at the cold junction and hot junction sides, respectively, at a 30 °C room temperature.

Continuous air conditioning is crucial for egg-hatching, chicken growth, and reproduction units [33,34,35,36,37,38]. However, frequent power cuts can disrupt the constant air conditioning supply, especially in remote locations. Solar energy offers a promising alternative solution: utilizing solar photovoltaic (PV) panels to provide a continuous power supply. Among the various types of solar PV panels available, monocrystalline solar panels are highly efficient and offer several advantages, such as reduced space requirements, durability, long lifespan, high-temperature tolerance, low light performance, and high-power output. The only drawback is the higher cost of these panels compared to other types.

A solar charge controller is essential for safely charging a battery through a solar panel. It regulates the solar voltage to the required battery voltage level (usually 12 volts DC), regardless of the irradiation levels falling on the solar panel. Maximum Power Point Tracking (MPPT) charge controllers are widely used among the many available charge controllers. The use of MPPT charge controllers in the proposed research offers several benefits, including increased energy harvesting, high energy conversion efficiency, adaptability to environmental changes, and adequate battery charging management. The MPPT algorithm extracts the maximum electrical power from the solar panel under all environmental conditions, as illustrated in Figure 1.

The proposed system utilizes a solar-powered thermoelectric module, TEC1-12703, with a solar panel, an MPPT charge controller, and battery power to provide continuous air conditioning. During the day, the battery stores electrical energy by charging with the solar panel via the MPPT charge controller. This stored energy is then released during nighttime or cloudy conditions, when solar irradiation is absent, ensuring the uninterrupted operation of the thermoelectric module. The choice of battery depends on various factors, such as voltage compatibility, capacity, chemistry, size, weight, cycling performance, temperature range, discharge rate, and cost. A lead–acid battery is selected for its high compatibility with the proposed system.

High-accuracy temperature sensors, such as infrared (IR) thermocouple sensors, are placed on both the cold and hot junction sides of the Peltier module to monitor temperature variations, as poultry chickens are sensitive to thermal fluctuations. Maintaining temperatures and humidity within specific limits is crucial for egg hatching and chicken production [38,39,40,41,42,43]. A thermocouple-based controller is integrated with the TEC-12703 Peltier module to maintain a steady temperature.

Figure 2 illustrates the proposed air conditioning method for egg-hatching, chicken-growing, and reproduction units. Compared to existing poultry systems, the proposed system offers simultaneous cooling and heating effects using only two Peltier modules, two temperature controllers, and a solar panel with a battery equipped with an MPPT charge controller. This innovative approach is highly effective, economical, renewable, and energy efficient, setting it apart from previously reported air conditioning systems in the literature.

This paper is structured into five sections: introduction, system overview and components, mathematical modeling and design calculations, hardware results and analysis, and conclusions and future scope. Section 1 provides a comprehensive introduction to the topic, while Section 2 describes the block diagram of the proposed research and its various components. Section 3 delves into the mathematical modeling and design calculations, while Section 4 presents the hardware results and analysis. Finally, Section 5 summarizes the conclusions and discusses the future scope of this research.

2. System Overview and Components

Figure 2 presents a block diagram of the proposed research system. The hot junction of the Peltier module is connected to the egg-hatching unit, while the cold junction is connected to the chicken-growing and reproduction unit. The Peltier module requires a DC power supply to operate, which is provided through a solar panel, an MPPT charge controller, and a battery. Two temperature sensors are connected at each junction to measure the temperatures over time, and a temperature controller is connected to both junctions to maintain the temperature within the desired ranges. Two exhaust fans are placed at the egg-hatching unit for air heating, while two cooling fans are located at the chicken-growing and reproduction unit.

The solar panel provides continuous electrical energy during the daytime, which is stored in a battery through the MPPT charge controller. The charge controller plays a crucial role in safely charging the battery, irrespective of variations in solar irradiation, by maintaining a constant output voltage required for battery charging. Temperature and humidity sensors and controllers are installed at both the egg-hatching and chicken-growing units. Upon sensing the temperatures at both units, the controllers intelligently operate the Peltier modules to maintain the desired temperatures. Two brushless DC (BLDC) fans are mounted for hot air circulation at the egg-hatching unit, and two BLDC fans are placed for cool air circulation at the chicken-growing unit.

3. Mathematical Modelling and Design Calculations

To better understand the proposed system, the mathematical modeling of the thermoelectric module and the solar-powered thermoelectric module are performed separately. This section presents the theoretical background and equations governing the system’s performance.

3.1. Mathematical Modelling of Thermoelectric Module

The performance of the Peltier module is measured by the figure of merit (FOM) [44], which is given by (1)

$$\mathrm{F}\mathrm{O}\mathrm{M}=\frac{\alpha }{\rho k}T$$

(1)

where

• T—absolute temperature;
• $\alpha$—Seebeck constant;
• $\rho$—electrical resistivity;
• k—thermal conductivity.

For an ideal latest third-generation Peltier module, the FOM is approximately equal to three [44,45,46,47]. As the FOM increases, the energy conversion efficiency of the Peltier module increases, whereas it decreases with increasing thermal conductivity [44,45,46,47].

The rate of thermal transfer per unit area ($Q_c$) is given by (2):

$$Q_c=\alpha TJ-k\nabla$$

(2)

where J is the electron density, k is the heat conductivity, and $\nabla$ is the gradient.

The heat diffusion equation at the steady state is given by (3):

$$\nabla \left(k\nabla T\right)+J^2\rho -T\frac{d\alpha }{dT}J·\nabla T=0$$

(3)

From (3), the first term represents heat conduction, the second term represents joule heating, and the third term represents the Thomson effect.

Assuming that $\alpha$ is not dependent on temperature, electrical or thermal contact resistance, or heat loss, then (3) is reduced to (4):

$$\frac{d}{dx}\left(kA\frac{dT}{dx}\right)+\frac{I^2\mathsf{\rho }}{A}$$

(4)

A—cross-sectional area, I—the current flowing through the module.

Equation (2), in the form of p-type and n-type semiconductors, is given by (5):

$$Q_c=\mathrm{n}\left[\left({\mathsf{\alpha }}_p-{\mathsf{\alpha }}_n\right)T_{c}I+{\left(-kA{\left.\frac{dT}{dx}\right|}_{x=0}\right)}_p+{\left(-kA{\left.\frac{dT}{dx}\right|}_{x=0}\right)}_n\right]$$

(5)

where $n$ is the number of thermocouples, $Q_c$ is the rate of heat absorbed at the cold side, ${\alpha }_p$ and ${\alpha }_n$ are the Seebeck coefficients at the p and n sides, $T_c$ is the temperature at the cool side, $I$ is the current flowing through the module, $A$ is the cross-sectional area, $\frac{dT}{dx}$ is the temperature gradient, and $L$ is thermocouple length.

The temperature gradient, with two boundary conditions (${\left.\frac{dT}{dx}\right|}_{x=0}$), is given by (6):

$${\left.\frac{dT}{dx}\right|}_{x=0}=\frac{I^2\rho L}{2A^{2}k}+\frac{T_h-T_c}{L}$$

(6)

Substituting (6) in (5) yields (7):

$$Q_c=n\left[\left({\alpha }_p-{\alpha }_n\right)T_{c}I-\frac{1}{2}{I}^2\left(\frac{{\rho }_p{L}_p}{A_p}+\frac{{\rho }_n{L}_n}{A_n}\right)-\left(\frac{k_p{A}_p}{L_p}+\frac{k_n{A}_n}{L_n}\right)\left(T_h-T_c\right)\right]$$

(7)

where

• $L_p$—the length of the thermocouple on the p side;
• $L_n$—the length of the thermowell at the n side;
• $A_P$—the thermocouple area of the cross section on the p side;
• $A_n$—the thermocouple area of the cross section on the n side;
• $k_p$—the thermal conductivity at p side of the thermocouple;
• $k_n$—the thermal conductivity at the n-sided thermocouple;
• $T_h$—the temperature at the hot side of the thermocouple;
• $n$—the number of thermocouples.

Assuming that the p-type and n-type thermocouples are similar, (7) becomes (8):

$$Q_c=n\left[(\alpha T_{c}I-\frac{1}{2}{I}^{2}R-k(T_h-T_c)\right]$$

(8)

where $\alpha$ = ${\alpha }_p-{\alpha }_n$ $R$—resistance.

$$R=\left(\frac{{\rho }_p{L}_p}{A_p}+\frac{{\rho }_n{L}_n}{A_n}\right)$$

$$k=\frac{k_p{A}_p}{L_p}+\frac{k_n{A}_n}{L_n}$$

The heat ejected at the hot junction ($Q_h$) is given by (9):

$$Q_h=n\left[(\alpha T_{h}I+\frac{1}{2}{I}^{2}R-k(T_h-T_c)\right]$$

(9)

where $R=\frac{\rho A}{L}$; $k=\frac{kA}{L}$.

The work performed per unit time ($W$) across the module is given by (10):

$$W=Q_h-Q_c$$

$$W=n\left(\alpha \left(T_h-T_c\right)I+I^{2}R\right)$$

(10)

The voltage ($V$) across the module is given by (11):

$$V=\frac{W}{I}=n\left(\alpha \left(T_h-T_c\right)+IR\right)$$

(11)

The coefficient of performance (COP) is defined as the ratio of the cooling power ($Q_c$) to the input electrical power ($W$) and is given by (12) [48,49,50,51,52].

$$COP=\frac{Q_c}{W}=\frac{n\left[(\alpha T_{c}I-\frac{1}{2}{I}^{2}R-k(T_h-T_c)\right]}{n\left(\alpha \left(T_h-T_c\right)I+I^{2}R\right)}$$

(12)

The current ($I_{COP}$) at which the maximum COP is achieved by differentiating (13) with respect to the current $I$ and made equal to zero is given by (13):

$$\frac{d\left(COP\right)}{dI}=0$$

(13)

The current ($I_{COP}$) is given by (14):

$$I_{COP}=\frac{\alpha \mathsf{\Delta }T}{R\left(\sqrt{1+z\overline{T}}-1\right)}$$

(14)

where $\mathsf{\Delta }T=T_h-T_c,z=\frac{{\alpha }^2}{\rho k}$ is also known as the FOM, and $\overline{T}$ is the average temperature of $T_c$ and $T_h$.

The current ($I_{mpc}$) at which the maximum cooling power is achieved by differentiating (8) with respect to the current $I$, which is made equal to zero, is given by (15):

$$\frac{d\left(Q_c\right)}{dI}=0$$

(15)

The current ($I_{mpc}$) is given by (16):

$$I_{mpc}=\frac{\alpha T_c}{R}$$

(16)

The current ($I_{mph}$) at which the maximum heating power is achieved by differentiating (9) with respect to the current $I$, which is made equal to zero, is given by (17):

$$\frac{d\left(Q_h\right)}{dI}=0$$

(17)

The current ($I_{mph}$) is given by (18):

$$I_{mph}=-\frac{\alpha T_h}{R}$$

(18)

The maximum current ($I_{max}$) that generates the maximum possible temperature difference is given by (19):

$$I_{max}=\frac{\alpha }{R}\left(\sqrt{{\left(T_h+\frac{1}{z}\right)}^2-{T_h}^2}-\frac{1}{z}\right)$$

(19)

The maximum temperature difference ($\mathsf{\Delta }{T}_{max}$) is given by (20):

$$\mathsf{\Delta }{T}_{max}=\left(T_h+\frac{1}{z}\right)-\sqrt{(T_h+\frac{1}{z}{)}^2-{T_h}^2}$$

(20)

The maximum cooling power ($Q_{cmax}$) is given by (21):

$$Q_{cmax}=\frac{n{\alpha }^2\left({T_h}^2-\Delta {T_{max}}^2\right)}{2R}$$

(21)

The maximum DC voltage ($V_{max}$) is given by (22):

$$V_{max}=n\alpha T_h$$

(22)

The material properties ($\alpha ,\rho ,k$) in a Peltier module are inversely proportional to the maximum parameters ($I_{max},\mathsf{\Delta }{T}_{max},Q_{cmax},V_{max}$) [53,54,55,56,57]. The material properties play an important role in predicting the performance of the Peltier module. For the effective operation of the Peltier module, the inverse proportion between the material properties and maximum parameters must be eliminated by introducing the effective FOM ($z^{\ast }$), Seebeck coefficient (${\alpha }^{\ast })$, electrical resistivity (${\rho }^{\ast }$), and thermal conductivity ($k^{\ast }$) [57,58,59,60,61,62,63,64,65,66].

The effective FOM ($z^{\ast }$) is given by (23):

$$z^{\ast }=\frac{2\mathsf{\Delta }{T}_{max}}{{\left(T_h-\mathsf{\Delta }{T}_{max}\right)}^2}$$

(23)

The effective Seebeck coefficient (${\alpha }^{\ast }$) is given by (24):

$${\alpha }^{\ast }=\frac{2{Q_c}_{max}}{n{I}_{max}\left(T_h+\mathsf{\Delta }{T}_{max}\right)}$$

(24)

The effective electrical resistivity (${\rho }^{\ast }$) is given by (25):

$${\rho }^{\ast }=\frac{{\alpha }^{\ast }\left(T_h\mathsf{\Delta }{T}_{max}\right)A/L}{I_{max}}$$

(25)

The effective thermal conductivity ($k^{\ast }$) is given by (26):

$$k^{\ast }=\frac{{{\alpha }^{\ast }}^2}{{\rho }^{\ast }{Z}^{\ast }}$$

(26)

The performance of the Peltier module can be seen by deriving the normalized values. The formula for the normalized value is given by (27):

$$Normalized=\frac{Actual}{Maximum}$$

(27)

The normalized value for the cooling power is given by (28):

$$\frac{Q_C}{Q_{max}}=\frac{n\left(\alpha \left(T_h-\mathsf{\Delta }T\right)I-\frac{1}{2}{I}^{2}R-k\mathsf{\Delta }T\right)}{n{\alpha }^2\left({T_h}^2-\mathsf{\Delta }{T_{max}}^2\right)/2R}$$

(28)

Formula (28), in terms of the normalized current and normalized temperature difference, is given by (29):

$$\frac{Q_c}{Q_{cmax}}=\frac{2\left(1-\frac{\mathsf{\Delta }T}{\mathsf{\Delta }{T}_{max}}\frac{\mathsf{\Delta }{T}_{max}}{T_h}\right)\frac{I}{I_{max}}}{1+\frac{\mathsf{\Delta }{T}_{max}}{T_h}}-\frac{\left(1-\frac{\mathsf{\Delta }{T}_{max}}{T_h}\right){\left(\frac{I}{I_{max}}\right)}^2}{1+\frac{\mathsf{\Delta }{T}_{max}}{T_h}}-\frac{2\frac{\mathsf{\Delta }T}{\mathsf{\Delta }{T}_{max}}\frac{\mathsf{\Delta }{T}_{max}}{T_h}}{Z{T}_h\left[1-{\left(\frac{\mathsf{\Delta }{T}_{max}}{T_h}\right)}^2\right]}$$

(29)

The normalized value for heating power is given by (30):

$$\frac{Q_h}{Q_{max}}=\frac{n\left(\alpha \left(T_c-\mathsf{\Delta }T\right)I+\frac{1}{2}{I}^{2}R-k\mathsf{\Delta }T\right)}{n{\alpha }^2\left({T_c}^2-\mathsf{\Delta }{T_{max}}^2\right)/2R}$$

(30)

Formula (30), in terms of the normalized current and normalized temperature difference, is given by (31):

$$\frac{Q_h}{Q_{hmax}}=\frac{2\left(1+\frac{\mathsf{\Delta }T}{\mathsf{\Delta }{T}_{max}}\frac{\mathsf{\Delta }{T}_{max}}{T_c}\right)\frac{I}{I_{max}}}{1+\frac{\mathsf{\Delta }{T}_{max}}{T_c}}-\frac{\left(1+\frac{\mathsf{\Delta }{T}_{max}}{T_c}\right){\left(\frac{I}{I_{max}}\right)}^2}{1+\frac{\mathsf{\Delta }{T}_{max}}{T_c}}-\frac{2\frac{\mathsf{\Delta }T}{\mathsf{\Delta }{T}_{max}}\frac{\mathsf{\Delta }{T}_{max}}{T_h}}{Z{T}_c\left[1-{\left(\frac{\mathsf{\Delta }{T}_{max}}{T_c}\right)}^2\right]}$$

(31)

The normalized COP for cooling is given by (32):

$$CO{P}_{cool}=\frac{\left(1-\frac{\mathsf{\Delta }T}{\mathsf{\Delta }{T}_{max}}\frac{\mathsf{\Delta }{T}_{max}}{T_h}\right)\frac{I}{I_{max}}-\frac{1}{2}\left(1-\frac{\mathsf{\Delta }{T}_{max}}{T_h}\right){\left(\frac{I}{I_{max}}\right)}^2-\frac{\frac{\mathsf{\Delta }T}{\mathsf{\Delta }{T}_{max}}\frac{\mathsf{\Delta }{T}_{max}}{T_h}}{Z{T}_h\left(1-\frac{\mathsf{\Delta }{T}_{max}}{T_h}\right)}}{\frac{\mathsf{\Delta }T}{\mathsf{\Delta }{T}_{max}}\frac{\mathsf{\Delta }{T}_{max}}{T_h}\frac{I}{I_{max}}+\left(1-\frac{\mathsf{\Delta }{T}_{max}}{T_h}\right){\left(\frac{I}{I_{max}}\right)}^2}$$

(32)

The normalized COP for heating is given by (33):

$$CO{P}_{heat}=\frac{\left(1+\frac{\mathsf{\Delta }T}{\mathsf{\Delta }{T}_{max}}\frac{\mathsf{\Delta }{T}_{max}}{T_c}\right)\frac{I}{I_{max}}-\frac{1}{2}\left(1+\frac{\mathsf{\Delta }{T}_{max}}{T_c}\right){\left(\frac{I}{I_{max}}\right)}^2-\frac{\frac{\mathsf{\Delta }T}{\mathsf{\Delta }{T}_{max}}\frac{\mathsf{\Delta }{T}_{max}}{T_c}}{Z{T}_c\left(1-\frac{\mathsf{\Delta }{T}_{max}}{T_c}\right)}}{\left(1+\frac{\mathsf{\Delta }{T}_{max}}{T_c}\right){\left(\frac{I}{I_{max}}\right)}^2-\frac{\mathsf{\Delta }T}{\mathsf{\Delta }{T}_{max}}\frac{\mathsf{\Delta }{T}_{max}}{T_c}\frac{I}{I_{max}}}$$

(33)

3.2. Mathematical Modelling of Solar Thermoelectric Module

The efficiency of the solar panel (${\eta }_{solar}$) is given by (34):

$${\eta }_{solar}=\frac{W_e}{I_p\times A_s}$$

(34)

where

• $W_e$ is the electrical power in kilowatt (kW).
• $A_s$—solar panel cross-sectional area (square meter);
• $I_p$—solar irradiation (kW/square meter).

The Peltier module efficiency at the cold side (${\eta }_{cold}$) is given by (35):

$${\eta }_{cold}=\frac{Q_c}{W_e}$$

(35)

The Peltier module efficiency at the hot side (${\eta }_{hot}$) is given by (36):

$${\eta }_{hot}=\frac{Q_h}{W_e}$$

(36)

The overall efficiency of the solar thermoelectric Peltier module (${\eta }_{solar-peltier}$) is given by (37) and (38):

$${\eta }_{solar-peltier}={\eta }_{solar}\times {\eta }_{cold}\times {\eta }_{hot}$$

(37)

$${\eta }_{solar-peltier}=\frac{Q_c{Q}_h}{I_p{A}_s{W_e}^2}$$

(38)

3.3. Design Calculations

The hardware components required to execute the proposed research are as follows:

(1)

Monocrystalline solar panel;

(2)

MPPT solar charge controller;

(3)

Lead–acid tubular battery;

(4)

Two Peltier modules;

(5)

Two heat sinks;

(6)

Two temperature sensors;

(7)

Two temperature controllers;

(8)

Two exhaust and two cooling fans.

The TEC-12703 Peltier module is rated at 12 V DC and 3 amp. of current. Two Peltier modules are used to achieve maximum cooling and heating efficiency, consuming a total power of 72 W (3 A × 12 V × 2). The fans placed at the hot and cold junctions consume an additional 6.72 W (2 × 2.16 W + 2 × 1.2 W). During the daylight hours, the solar panel should be capable of delivering 80.64 W to power the Peltier modules and fans while also charging the battery. Assuming an average of 10 h of irradiation per day, the solar panel capacity is calculated as follows:

Solar panel capacity = Peltier module power + Fan power = 72 W + 6.72 W = 79.72 W

To ensure continuous operation during periods without sunlight, the system must be designed to sustain a load of 80.64 W for 12 h. The energy required from the battery is calculated as follows:

Energy = Power × Time = 80.64 W × 12 h = 967.68 Wh

Considering inefficiencies and losses, an additional 20% of the energy is added, resulting in a total required energy of

Total required energy = 967.68 Wh × 1.2 ≈ 1161.21 Wh

Given an average of 4 peak sunlight hours per day, the required solar panel output is as follows:

Solar panel output = Total required energy ÷ Peak sunlight hours = 1161.21 Wh ÷ 4 h ≈ 290.30 W

Therefore, a solar panel with an approximate output of 290.30 W is needed to continuously deliver 80.64 W of power, with battery support for 12 h without sunlight. The battery capacity is calculated as follows:

Battery capacity (Ah) = Total required energy (Wh) ÷ Battery voltage (V) = 1161.21 Wh ÷ 12 V ≈ 96.76 Ah

A 12 V, 100 Ah lead–acid battery is selected, considering a 20% safety margin for losses. Temperature control is achieved using XH-W1209 adjustable temperature controllers, one for each side of the egg-hatching and chicken-farming units.

The MPPT charge controller is sized based on the solar panel and battery specifications. For a 300 W solar panel with a typical voltage range of 17–18 V and a 12 V, 100 Ah battery, the following steps are used to determine the appropriate MPPT charge controller:

Calculate the current: I = P ÷ V = 300 W ÷ 17 V ≈ 17.64 A.

Apply a 25% oversizing factor: 17.64 A × 1.25 = 22.05 A.

Select an MPPT charge controller rated at least 30–40 A to accommodate the calculated current and oversizing factor.

Heat transfer calculations are required to increase the room size for the egg-hatching and the chicken-growing and reproduction units.

4. Hardware Results and Analysis

This section will initially explain the block diagram of the proposed research prototype, the steps in validating the hardware, and its analysis by comparing various existing egg-hatching and chicken-growing and reproduction units.

4.1. Block Diagram of the Proposed Hardware

The complete hardware setup for the proposed egg-hatching, chicken-growing, and reproduction units is shown in Figure 3. From the design calculations, a 12-volt, 300-watt monocrystalline solar panel is placed under continuous solar irradiation, irrespective of day and night. Due to the variations in the solar irradiation levels, the solar panel output voltage also fluctuates. To avoid these fluctuations, an MPPT solar charge controller with a rating of 12 volts and 40 amp is connected to the output of the solar panel. The duty of the solar charge controller is to maintain a constant DC voltage for the safe charging of the solar battery. The output of the solar charge controller is connected to a solar battery with a rating of 12 volts and 100 Ah. This battery is capable of delivering the power required for the proposed setup continuously for 12 h even though no irradiation occurs. The output of the battery is connected to two temperature controllers of each 12-volt, 10amp rating. One temperature controller is connected to a sensor, and the output is connected to the hot side of Peltier module 1, i.e., at the egg-hatching unit. Another temperature controller is connected to the cold side of Peltier module 2, i.e., the chicken-growing and reproduction unit. Two fans on the hot side and two fans on the cold side of the Peltier modules are connected for uniform air circulation on the hot and cold sides, respectively. The egg-hatching unit requires 35 to 40 degrees centigrade of temperature. Hence, the on and off temperatures are set in the controller. Similarly, the temperature will be set for the controller placed at the chicken-growing and reproduction units. At the egg-hatching unit, two hot junctions are placed from two Peltier modules, but the temperature controller is connected to the hot side of Peltier module 1, and the other hot junction is controlled by the temperature controller placed in the chicken-growing and reproduction unit and vice versa. This kind of temperature control will optimize the overall performance and reduce costs.

4.2. Steps in Validating the Proposed Hardware Setup

The steps for validating the proposed research idea are shown in Figure 4. Initially, the Peltier modules (TEC1-12703) were tested with a switched mode power supply (SMPS) for cooling and heat effects on each cold and hot junction. Next, the temperature sensors and controllers were tested for sensing and controlling the temperature, and the entire proposed setup was tested with the SMPS. After testing the entire proposed setup with the SMPS, the whole assembly was tested with a monocrystalline solar panel as an input to the Peltier modules through the lead–acid battery and MPPT charge controller.

4.2.1. Testing of Peltier Module 1 and 2

Each Peltier module consists of a TEC1-12703 Peltier plate, two heat sinks, and two fans on each side. TEC1-12703 demands a 12-volt DC supply, and it draws a maximum current of 3 amp. Initially, for the SMPS with a 12-volt DC rating, 10 amp was used as the power source. A temperature sensor is connected to a heat sink placed on the cold side. Table 1 shows that TEC1-12703 is the best Peltier module for cooling applications. Similarly, TEC-12703 was also tested on the hot side. Table 2 shows that TEC1-12703 is the best Peltier module even for heating applications.

4.2.2. Testing of Temperature Controllers

The connection diagram of the temperature controller is shown in Figure 5. To control the Peltier module, a 12-volt DC supply is connected to the temperature controller input terminals, and the output terminals are connected to the Peltier module. The input of the sensor is connected to the controller, and the sensor is placed on either the cold or hot side, based on the sensor requirements. The sensed temperature will be used to control the Peltier module by setting the up and down temperatures. For the egg-hatching unit, the set temperatures were between 35 and 40 °C. The controller switches on the Peltier module when the temperature falls below 35 °C and switches it off when it exceeds 40 °C. Similarly, for the chicken-growing and reproduction unit, the temperature ranges between 10 and 24 °C. The controller switches on the Peltier module when the temperature exceeds 24 °C and switches it off when it falls below 10 °C.

In the next step, the testing of the temperature controller with the Peltier module and SMPS is performed. The temperature controller is able to maintain the temperatures required for egg hatching, chicken growth, and reproduction by controlling the Peltier modules based on the sensed temperatures at the hot and cold sides.

4.2.3. Testing of the Whole Assembly with the SMPS

After testing the Peltier modules, the sensor, and the temperature controller separately using the SMPS, the whole setup was tested with the SMPS, as shown in Figure 6. The hot sides of the Peltier modules 1 and 2 are projected to the egg-hatching unit, and the cold sides are projected to the chicken-growing and reproduction unit. One sensor was placed in the egg-hatching unit, and one sensor was placed in the chicken-growing and reproduction unit. The whole assembly perfectly maintained the temperatures required for the egg-hatching and chicken-growing and reproduction units. For the uniform distribution of heat throughout the egg-hatching unit, two fans were used, and another two fans were used at the chicken-growing and reproduction unit for the uniform distribution of cool air.

4.2.4. Testing of Whole Assembly with Solar Panel, Charge Controller, and Battery

To facilitate the proposed air conditioning system for egg hatching, a chicken-growing and reproduction unit for off-grid chicken farmers and zero electrical energy bills for existing chicken farmers, the proposed air conditioning system was fed with solar energy through a solar panel, an MPPT charge controller, and a battery, as shown in Figure 7. The proposed system is designed so that both the egg-hatching and chicken farms will run continuously, without any power interruption. This kind of air conditioning with solar energy is not mentioned anywhere in the literature, and it is novel in the current research.

The temperatures achieved with the proposed solar thermoelectric module with respect to time at the cold side are shown in

Table 3. Temperatures achieved at the cold side.

Chicken-Growing and Reproduction Unit	Current in Amperes	Time in Minutes	Temperature in °C
	2.51	5	30
	2.64	10	28
	2.83	15	25
	2.92	20	22
	3.05	25	21
	3.12	30	20
	3.14	35	19
	3.15	40	17
	3.19	45	15
	3.21	50	12
	3.23	55	10

. The ambient room temperature was 35 °C.

The temperatures achieved with the proposed solar thermoelectric module with respect to time at the hot side are shown in

Table 4. Temperatures achieved at the hot side.

Egg-Hatching Unit	Current in Amperes	Time in Minutes	Temperature in °C
	2.51	5	38
	2.64	10	41
	2.83	15	42
	2.92	20	44
	3.05	25	45
	3.12	30	46
	3.14	35	47
	3.15	40	48
	3.19	45	50
	3.21	50	51
	3.23	55	52

. The ambient room temperature was 35 °C.

From Table 3 and Table 4, it is evident that the proposed solar thermoelectric module is capable of performing the cooling action for the chicken-growing and reproduction unit and the heating action for the egg-hatching unit. Additionally, the temperature controllers placed at both sides will maintain the temperatures required according to existing standards. The addition of temperature controllers will optimize the entire proposed setup by switching the solar thermoelectric module on and off in accordance with the set temperatures on both sides.

A comparison of the proposed air conditioning system for the egg-hatching unit with existing methods is given in

Table 5. Comparison of air conditioning systems for the egg-hatching unit.

	Cost	Efficiency	Reliability	Production	Renewable	Energy Bills	COx Emissions	Payback
Natural incubation	Moderate	Less	Less	Less	No	Moderate	Low	Not Applicable
Tube light incubation	High	Less	Less	Medium	No	Moderate	Low	Not Applicable
Forced air incubation	High	Moderate	Moderate	Medium	No	High	Moderate	Not Applicable
Still air incubation	High	Moderate	Moderate	Medium	No	High	Moderate	Not Applicable
Thermostat air incubation	High	Moderate	Less	Medium	No	High	Moderate	Not Applicable
Proposed method	Low	High	High	High	Yes	Zero	Zero	Applicable

.

A comparison of the proposed air conditioning system for the chicken-growing and reproduction unit is given in

Table 6. Comparison of air conditioning systems for the chicken-growing and reproduction unit.

	Cost	Efficiency	Reliability	Production	Renewable	Energy Bills	COx Emissions	Payback
Mechanical ventilation	Moderate	Less	Less	Less	No	Moderate	Low	Not Applicable
Evaporative cooling	Moderate	Less	Less	Medium	No	Moderate	Low	Not Applicable
Refrigerant cooling	High	High	Moderate	Medium	No	High	High	Not Applicable
Natural ventilation	Low	Moderate	Less	Medium	Yes	High	Zero	Not Applicable
Insulation and thermal regulation	High	Moderate	Less	Medium	No	High	Moderate	Not Applicable
Proposed method	Low	Moderate	High	Medium	Yes	Zero	Zero	Applicable

.

A list of hardware components used to implement the proposed research along with type, specifications, and parameters is given in

Table 7. List of hardware components with type and rating.

Hardware Component	Type	Rating
Solar panel	Monocrystalline	12 Volt, 300 watts
Solar charge controller	MPPT	24/12 Volt, 50 Amps
Tubular battery	Lead–Acid	12 Volt, 100 Ah
Peltier modules and heat sinks	TEC1-12603	12 Volt, 3 Amps
Cooling fans	BLDC motor	12 Volt, 1.8 watts
Heating fans	BLDC motor	12 Volt, 3 watts
Temperature controllers with sensors	Thermocouple	12 Volt, 10 Amps
Switched mode power supply	-	12 Volt, 10 Amps

.

5. Conclusions

The proposed solar-powered thermoelectric air conditioning system presents a novel, energy-efficient, and eco-friendly solution for poultry farmers. Compared to conventional cooling methods, this system significantly reduces energy costs, minimizes space requirements, operates quietly, and eliminates the need for harmful refrigerant gases. The improved energy efficiency and reduced CO₂ emissions contribute to the overall sustainability of poultry farming operations.

The economic analysis revealed that the proposed system offers a relatively short payback period and substantial long-term cost savings for poultry farmers. Moreover, the optimal thermal management provided by the system can enhance animal welfare and increase productivity by improving egg-hatching rates and reducing poultry mortality. The modular design and adaptability of the proposed system make it easy to implement in existing poultry farms, offering a practical solution for farmers looking to upgrade their climate control systems. The reliance on renewable solar energy makes it particularly suitable for remote locations with limited access to the electricity grid, expanding the potential adoption of this technology.

This research contributes to precision agriculture, renewable energy applications, and climate control in agricultural settings. The findings demonstrate the feasibility and benefits of integrating thermoelectric cooling with solar power in poultry farming, paving the way for further advancements in sustainable agricultural practices. However, some limitations and challenges should be considered, such as the potential for electromagnetic interference from solar panels and other components, the importance of proper grounding practices to avoid safety hazards and interference issues, and the impact of environmental conditions on the performance and reliability of the system.

Future research should focus on addressing these limitations while incorporating automatic egg turners, conducting detailed heat transfer calculations for optimal unit sizing, integrating humidity control mechanisms, and exploring the system’s scalability using high-capacity Peltier modules. Additionally, long-term studies on the system’s performance, durability, and maintenance requirements in real-world poultry farming environments would provide valuable insights for further optimization and widespread adoption.

Although the proposed solar-powered thermoelectric air conditioning system may have a relatively high initial cost due to the hardware components, it offers significant long-term benefits. The system requires minimal maintenance, with only the tubular battery needing occasional distilled water and the solar panels requiring regular cleaning. The Peltier modules, cooling and heating fans, and temperature sensors are designed to be maintenance-free. Over time, the system provides substantial cost savings in electricity bills, making it an economically viable solution. Moreover, the improved thermal management is expected to enhance poultry health and egg production, further compensating for the initial investment. Despite the initial cost and maintenance considerations, the proposed system presents a sustainable and efficient solution for poultry farming.

In conclusion, the proposed self-powered thermoelectric module offers a sustainable, low-maintenance, and cost-effective solution for air conditioning in poultry farms. With its potential to revolutionize the poultry farming industry by providing an optimized air conditioning solution for small-scale and large commercial poultry farms, this technology represents a significant step towards more sustainable and efficient agricultural practices.