**1. Introduction**

Air-conditioning (AC) is a basic need for thermal comfort of humans as well as for animals. Living space per capita in case of human is decreasing due to population increase; therefore, it is difficult to provide huge space to animals with high natural ventilation. Thus, compact size farms with good thermal comfort conditions are needed. For this purpose, many air-conditioning systems are being used globally. The conventional AC systems use almost half of the total energy which is a huge amount of primary energy. So, energy efficient AC systems are principally required for animals particularly for developing countries. In case of Pakistan, animals contribute about 70–75% of the total agricultural GDP share [1] which is huge number. Livestock is sometime neglected area of research in developing

countries e.g., Pakistan, Bangladesh, India, African countries etc. Therefore, the benefit from the livestock sector of such countries can be significantly increased by providing low-cost sustainable farm technologies [2]. Animals' thermal comfort includes the mechanisms of metabolism rate, skin heat transfer, rate of respiration, genetic factor and nature of feed, etc., [3–5]. That's why, it is important to air condition the space for animals to enhance the output products e.g., milk, fertility, meat and other related products etc., [2, 4, 6].

calculation for farm animals (Holstein Friesian Cow and Poultry application). Evaporative cooling and desiccant based air-conditioning systems are discussed according to the thermal comfort requirements for the animals. Jurinak model [9–13] is used for the evaluation of desiccant block and simplified correlations are used for performance evaluation of heat exchanger [14] and M-cycle cooling system [5]. Building designs and associated key factors affecting are also discussed for the subjected application. Moreover, the feasibility of systems is checked for the climatic conditions of Multan, Pakistan. Some other authors [15–18] also evaluate for animal applications the different AC systems (desiccant based and evaporative

*Investigation of Desiccant and Evaporative Cooling Systems for Animal Air-Conditioning*

The novelty of this book chapter is to introduce the methods to calculate the heat load calculations for Holstein Friesian cows and poultry applications for the climatic conditions of Multan, Pakistan. The AC systems (standalone and combined) proposed for animal air-conditioning are not used for discussed applications before for

cooling-based systems) for different ventilation arrangements.

**2. Ventilation rate and building designs for animal housings**

the key parameter to measure and to create the thermal comfort.

**2.2 Climate control and farm building designs**

**23**

Ventilation is one of the important techniques used to control the thermal stresses in case of animals. Lots of studies have showed the significance of ventilation rate for achieving the ideal thermal comfort, and thereby, ventilation rate is considered an essential parameter for animal air-conditioning [5, 15, 16–19]. For example, **Figure 2** shows the factors affecting the selection of ventilation rate [20]. The suffocation or level of O2/CO2 is usually controlled by the air flow rate which must be designed precisely depending upon the nature of application. For livestock applications, ventilation is highly required to avoid the heat stress condition especially dairy cattle [17–20]. Dairy products, meat production, and other livestock applications need enough oxygen for longer storage period especially at commercial level. The ventilation rate depends upon the nature of the application and the climatic condition of the area for which the AC is needed [5, 21, 22]. It is considered

Advanced animals' AC options are limited in developing countries due to high initial and maintenance cost. Small farmers/stake holders cannot afford much cost. In addition, building designs are not very efficient in terms of providing thermal comfort to the farm animals [5, 7, 23]. In many developing countries including Pakistan, open side walls covered with sieve like material (natural ventilation) are used for cross flow of air with a flat roof [24]. Natural ventilation is good in maintaining the temperature, humidity and suffocation in cattle barns especially [23]. Instead, mechanical ventilation (active or passive) avoids the excess amount of carbon dioxide and ammonia in the air which can cause diseases and growth rate declination. Furthermore, the building designs can be further modified with respect to ventilation requirements and thermal comfort requirements [5, 7, 8, 23]. In this regard, researchers use different types of ventilation orientations [3, 5, 23, 25]. First type of ventilation is base ventilation as shown in **Figure 3a**. Negative pressure is created by lateral fans inside the house ejecting the exhaust air outside (brown arrows). Supply clean air (green arrows) is entered through the windows on the opposite wall that creates ventilation flow in the cross direction that guarantees

the climatic conditions of Multan, Pakistan.

*DOI: http://dx.doi.org/10.5772/intechopen.88945*

**2.1 Significance of ventilation rate**

**Figure 1** shows the illustration of the different heat transfer phenomena between environment and animals and the psychrometric thermal comfort zones for different animal species [7]. Most commonly heat transfer phenomena are considered which govern the fundamental equations for load calculations. Similarly, comfort zones elaborate the limit of temperature and relative humidity required for the ideal growth of different species [5, 8].

This chapter focuses on ideal heat transfer and comfort zones for the different species of animals. A set of equations is used for the measurement of the heat load

**Figure 1.** *Simplified illustration of: (A) animals heat transfer phenomena, and (B) psychrometric thermal comfort zones for different animals.*

*Investigation of Desiccant and Evaporative Cooling Systems for Animal Air-Conditioning DOI: http://dx.doi.org/10.5772/intechopen.88945*

calculation for farm animals (Holstein Friesian Cow and Poultry application). Evaporative cooling and desiccant based air-conditioning systems are discussed according to the thermal comfort requirements for the animals. Jurinak model [9–13] is used for the evaluation of desiccant block and simplified correlations are used for performance evaluation of heat exchanger [14] and M-cycle cooling system [5]. Building designs and associated key factors affecting are also discussed for the subjected application. Moreover, the feasibility of systems is checked for the climatic conditions of Multan, Pakistan. Some other authors [15–18] also evaluate for animal applications the different AC systems (desiccant based and evaporative cooling-based systems) for different ventilation arrangements.

The novelty of this book chapter is to introduce the methods to calculate the heat load calculations for Holstein Friesian cows and poultry applications for the climatic conditions of Multan, Pakistan. The AC systems (standalone and combined) proposed for animal air-conditioning are not used for discussed applications before for the climatic conditions of Multan, Pakistan.

### **2. Ventilation rate and building designs for animal housings**

#### **2.1 Significance of ventilation rate**

countries e.g., Pakistan, Bangladesh, India, African countries etc. Therefore, the benefit from the livestock sector of such countries can be significantly increased by providing low-cost sustainable farm technologies [2]. Animals' thermal comfort includes the mechanisms of metabolism rate, skin heat transfer, rate of respiration, genetic factor and nature of feed, etc., [3–5]. That's why, it is important to air condition the space for animals to enhance the output products e.g., milk, fertility,

**Figure 1** shows the illustration of the different heat transfer phenomena between environment and animals and the psychrometric thermal comfort zones for different animal species [7]. Most commonly heat transfer phenomena are considered which govern the fundamental equations for load calculations. Similarly, comfort zones elaborate the limit of temperature and relative humidity required for

This chapter focuses on ideal heat transfer and comfort zones for the different species of animals. A set of equations is used for the measurement of the heat load

*Simplified illustration of: (A) animals heat transfer phenomena, and (B) psychrometric thermal comfort zones*

meat and other related products etc., [2, 4, 6].

*Low-temperature Technologies*

the ideal growth of different species [5, 8].

**Figure 1.**

**22**

*for different animals.*

Ventilation is one of the important techniques used to control the thermal stresses in case of animals. Lots of studies have showed the significance of ventilation rate for achieving the ideal thermal comfort, and thereby, ventilation rate is considered an essential parameter for animal air-conditioning [5, 15, 16–19]. For example, **Figure 2** shows the factors affecting the selection of ventilation rate [20]. The suffocation or level of O2/CO2 is usually controlled by the air flow rate which must be designed precisely depending upon the nature of application. For livestock applications, ventilation is highly required to avoid the heat stress condition especially dairy cattle [17–20]. Dairy products, meat production, and other livestock applications need enough oxygen for longer storage period especially at commercial level. The ventilation rate depends upon the nature of the application and the climatic condition of the area for which the AC is needed [5, 21, 22]. It is considered the key parameter to measure and to create the thermal comfort.

#### **2.2 Climate control and farm building designs**

Advanced animals' AC options are limited in developing countries due to high initial and maintenance cost. Small farmers/stake holders cannot afford much cost. In addition, building designs are not very efficient in terms of providing thermal comfort to the farm animals [5, 7, 23]. In many developing countries including Pakistan, open side walls covered with sieve like material (natural ventilation) are used for cross flow of air with a flat roof [24]. Natural ventilation is good in maintaining the temperature, humidity and suffocation in cattle barns especially [23]. Instead, mechanical ventilation (active or passive) avoids the excess amount of carbon dioxide and ammonia in the air which can cause diseases and growth rate declination. Furthermore, the building designs can be further modified with respect to ventilation requirements and thermal comfort requirements [5, 7, 8, 23]. In this regard, researchers use different types of ventilation orientations [3, 5, 23, 25].

First type of ventilation is base ventilation as shown in **Figure 3a**. Negative pressure is created by lateral fans inside the house ejecting the exhaust air outside (brown arrows). Supply clean air (green arrows) is entered through the windows on the opposite wall that creates ventilation flow in the cross direction that guarantees

#### **Figure 2.** *Selection of ventilation rate for livestock application [20].*

indoor air quality control. Base ventilation in rectangular shaped farm sheds which are used with fans at one end and the holes at roof and opposite side of the building which allows the cross flow of the air. Base flow is normally used to control indoor air quality for the circulation of the air which reduces the contaminants of harmful gases in the air [3, 25]. The second type of the ventilation is tunnel ventilation as shown in **Figure 3b**. This is due to the horizontal movement of air in the farm shed. There are greater number of fans used than that of base ventilation. It can be seen that the hot air is ejected through the fans placed at the end of the house outside (red arrows), that creates a negative pressure inside the building. Due to the pressure difference, fresh outdoor air is entered (blue arrows) through the inlets decreasing the indoor air temperature. In this type of ventilation, air temperature is decreased due to the removal of thermal emission of the animals and wind-chill effect is produced [3, 7, 14, 26]. Air speed does not exceed 3 ms<sup>1</sup> in this type of ventilation, otherwise thermal discomfort occurs. When tunnel ventilation is not enough to provide thermal comfort in the farm sheds, evaporative cooling systems are additionally used. The evaporative cooling (EC) shown in the **Figure 3c** converts sensible heat into latent which is carried out by evaporative pads. It can be seen that the negative pressure is created inside the house by the fans which lets the hot external air pass through the wet evaporative pads that decreases the air temperature (red/blue arrows). The indoor air temperature is decreased and is expelled by the tunnel ventilation fans (red arrows). During the warmest periods, ambient air passes through the evaporative pads where air is cooled due to evaporation of the water [3, 7, 8, 25]. This decreases the outlet air and consequently, indoor air temperature also decreases. Cooling pads are configured on the larger side of the

building wall opposite to the tunnel ventilation fans which allows the passage of

*Illustration of operating principle for: (a) base ventilation, (b) tunnel ventilation, and (c) evaporative*

*Investigation of Desiccant and Evaporative Cooling Systems for Animal Air-Conditioning*

*DOI: http://dx.doi.org/10.5772/intechopen.88945*

The side view of the evaporative pads used in the farm sheds is shown in **Figure 4a** and the schematic diagram of the evaporative cooling system as shown in the **Figure 4b**. Evaporative cooling (EC) is a system of water vapor evaporating into air that cools the air by water evaporation. In a study [7, 16], authors used honeycomb like structure for the evaporation supportive channel. In that channel, water is supplied from upside down with the help of a sprinkler. Air is passed through that honeycomb structure from one side to another side. The fan is used for the controlled flow of air in the system. There is a cylinder of water that collects water whereas a water pump is used to flow the water from the tank to the sprinkler as shown in **Figure 4b**. This can be a low-cost method to attain thermal comfort conditions in controlled sheds in hot climatic conditions except in rainy season

cooled air due to negative pressure [3].

(monsoon season).

**25**

**Figure 3.**

*cooling [3].*

*Investigation of Desiccant and Evaporative Cooling Systems for Animal Air-Conditioning DOI: http://dx.doi.org/10.5772/intechopen.88945*

**Figure 3.** *Illustration of operating principle for: (a) base ventilation, (b) tunnel ventilation, and (c) evaporative cooling [3].*

building wall opposite to the tunnel ventilation fans which allows the passage of cooled air due to negative pressure [3].

The side view of the evaporative pads used in the farm sheds is shown in **Figure 4a** and the schematic diagram of the evaporative cooling system as shown in the **Figure 4b**. Evaporative cooling (EC) is a system of water vapor evaporating into air that cools the air by water evaporation. In a study [7, 16], authors used honeycomb like structure for the evaporation supportive channel. In that channel, water is supplied from upside down with the help of a sprinkler. Air is passed through that honeycomb structure from one side to another side. The fan is used for the controlled flow of air in the system. There is a cylinder of water that collects water whereas a water pump is used to flow the water from the tank to the sprinkler as shown in **Figure 4b**. This can be a low-cost method to attain thermal comfort conditions in controlled sheds in hot climatic conditions except in rainy season (monsoon season).

indoor air quality control. Base ventilation in rectangular shaped farm sheds which are used with fans at one end and the holes at roof and opposite side of the building which allows the cross flow of the air. Base flow is normally used to control indoor air quality for the circulation of the air which reduces the contaminants of harmful gases in the air [3, 25]. The second type of the ventilation is tunnel ventilation as shown in **Figure 3b**. This is due to the horizontal movement of air in the farm shed. There are greater number of fans used than that of base ventilation. It can be seen that the hot air is ejected through the fans placed at the end of the house outside (red arrows), that creates a negative pressure inside the building. Due to the pressure difference, fresh outdoor air is entered (blue arrows) through the inlets decreasing the indoor air temperature. In this type of ventilation, air temperature is decreased due to the removal of thermal emission of the animals and wind-chill effect is produced [3, 7, 14, 26]. Air speed does not exceed 3 ms<sup>1</sup> in this type of ventilation, otherwise thermal discomfort occurs. When tunnel ventilation is not enough to provide thermal comfort in the farm sheds, evaporative cooling systems are additionally used. The evaporative cooling (EC) shown in the **Figure 3c** converts sensible heat into latent which is carried out by evaporative pads. It can be seen that the negative pressure is created inside the house by the fans which lets the hot external air pass through the wet evaporative pads that decreases the air temperature (red/blue arrows). The indoor air temperature is decreased and is expelled by the tunnel ventilation fans (red arrows). During the warmest periods, ambient air passes through the evaporative pads where air is cooled due to evaporation of the water [3, 7, 8, 25]. This decreases the outlet air and consequently, indoor air temperature also decreases. Cooling pads are configured on the larger side of the

**Figure 2.**

*Low-temperature Technologies*

**24**

*Selection of ventilation rate for livestock application [20].*

**Figure 4.** *A view of: (a) cellulose evaporative pads [3]; and (b) schematic diagram of evaporative cooling system [7].*
