**4.1 Case study – the Kharseh chicken farm**

The Kharseh chicken farm in Hama, Syria, was selected as a study case to show the contribution of ground source heat pumps in saving energy consumption of heating and cooling system. Even though the annual mean temperature in Syria is 15-18 oC, heating of such farm consumes considerable amounts of energy. The reason is that the air temperature is close to freezing during three winter months and that chickens require a relatively high temperature, 21-35 oC, depending on chickens' age as seen in Table. 1.


Table 1. Appropriate indoor temperature in chicken farms.

The chicken hangar is placed parallel to the main wind direction has a floor area of 500 m2 (50 m x 10 m) in E–W direction. The total window area is 24 m2.

#### **4.2 Heating/cooling demand**

The mean heating load composed of heat losses through the external walls and ventilation, while cooling load composed of heat gained through external walls, ventilation, solar radiation, and heat released by chickens. In current work the degree-hour method was used to estimate the thermal demand of the hangar (Durmayaz et al., 2000) using following assumptions:


Ground-Source Heat Pumps and Energy Saving 469

It should be noted that in Kharseh, 2009 the German DIN was used for the same aim.

Fig. 7. Heating/cooling power as function of chicken age for one complete cycle during the

The EED (Earth Energy Design) model(EED, 2008) was used in pre-designing required

borehole system to meet to estimated heating/cooling load at given conditions.

Therefore there is a small different in estimated thermal demand of the hangar.

Fig. 6. Monthly heating/cooling demand and solar yield.

hottest and coldest period.

**4.3.1 Borehole system** 

 Number of boreholes: 10 Borehole Diameter: 0.11 m Borehole Depth: 120 m

**4.3 System design and simulated operation** 

Specific data of the borehole system are given below:


Using these assumptions, the total heat loss coefficient of the hangar, L (W/K), can be calculated as follow:

$$L = \frac{(\rho \mathbf{C}\_p)\_{air} \cdot I \cdot V}{3600} + \Sigma \,\mathrm{U} \cdot A \tag{12}$$

Finally, annual heating demand, Qh (MWh), is

$$Q\_h = \frac{L \cdot DHh - 50 \cdot 500 \cdot 24 \cdot 30 \cdot 6}{10^6} \tag{13}$$

While the annual cooling demand, Qc (MWh), is

$$Q\_c = \frac{L \cdot DHc + 50 \cdot 500 \cdot 10 \cdot 30 \cdot 4}{10^6} \tag{14}$$

Where DHh and DHc is the total number of degree-hours of heating and cooling, respectively, which can be calculated as follow:

$$\text{DHI} = \sum\_{j=1}^{N} \left( T\_i - T\_o \right)\_j \qquad \text{when is} \quad T\_o \le T\_b \tag{15}$$

While for cooling (DHc)

$$DHc = \sum\_{j=1}^{K} \left(T\_o - T\_i\right)\_j \qquad \text{when is} \quad T\_o \ge T\_b \tag{16}$$

Where Tb is the base temperature and Ti represents the indoor design temperature, To is the hourly ambient air temperature measured at a meteorology station, N is the number of hours providing the condition of To≤Tb in a heating season while K is the number of hours providing the condition of To≥Tb in a cooling season. In current work, and due to considering the big internal load, base temperature was assumed to be equal to Ti. Since the indoor temperature varies with the time during chickens cycle, the indoor temperature was assumed to be constant during one cycle and equals the average temperature i.e. Ti=28 oC. Fig.6 shows that the estimated total annual heating demand is 230 MWh while the corresponding cooling demand is 33 MWh.

In order to determine the maximum required heating and cooling capacity, the required heating/cooling power as the chickens grow during the hottest and coldest period of the year were calculate. As shown in Fig. 7, during heating season, due to lowering the appropriate indoor temperature with age and due to increase the occupied area, the heating power increases with time until it peaks in the middle of the chickens' life cycle. This peak demand does not occur during the cooling season. The calculations showed that the maximum required heating and cooling capacity are 113 kW and 119 kW, respectively.

10 h of cooling and 24 hours of heating are required per a day during summer and

Using these assumptions, the total heat loss coefficient of the hangar, L (W/K), can be

6 50 500 24 30 6

6 50 500 10 30 4

*i o j o b*

*o i j o b*

Where DHh and DHc is the total number of degree-hours of heating and cooling,

*DHh T T when is T T*

*DHc T T when is T T*

Where Tb is the base temperature and Ti represents the indoor design temperature, To is the hourly ambient air temperature measured at a meteorology station, N is the number of hours providing the condition of To≤Tb in a heating season while K is the number of hours providing the condition of To≥Tb in a cooling season. In current work, and due to considering the big internal load, base temperature was assumed to be equal to Ti. Since the indoor temperature varies with the time during chickens cycle, the indoor temperature was assumed to be constant during one cycle and equals the average temperature i.e. Ti=28 oC. Fig.6 shows that the estimated total annual heating demand is 230 MWh while the

In order to determine the maximum required heating and cooling capacity, the required heating/cooling power as the chickens grow during the hottest and coldest period of the year were calculate. As shown in Fig. 7, during heating season, due to lowering the appropriate indoor temperature with age and due to increase the occupied area, the heating power increases with time until it peaks in the middle of the chickens' life cycle. This peak demand does not occur during the cooling season. The calculations showed that the maximum required heating and cooling capacity are 113 kW and 119 kW, respectively.

(12)

*L DHh <sup>Q</sup>* (13)

*L DHc <sup>Q</sup>* (14)

(15)

(16)

( )

10 *<sup>h</sup>*

10 *<sup>c</sup>*

( )

( )

1

1

*K*

*j*

*N*

*j*

3600 *C IV p air <sup>L</sup> U A*

Heating season is 6 months, while cooling season is 4 months.

winter, respectively.

Finally, annual heating demand, Qh (MWh), is

While the annual cooling demand, Qc (MWh), is

respectively, which can be calculated as follow:

corresponding cooling demand is 33 MWh.

calculated as follow:

While for cooling (DHc)

Fig. 6. Monthly heating/cooling demand and solar yield.

It should be noted that in Kharseh, 2009 the German DIN was used for the same aim. Therefore there is a small different in estimated thermal demand of the hangar.

Fig. 7. Heating/cooling power as function of chicken age for one complete cycle during the hottest and coldest period.

#### **4.3 System design and simulated operation**

The EED (Earth Energy Design) model(EED, 2008) was used in pre-designing required borehole system to meet to estimated heating/cooling load at given conditions.

#### **4.3.1 Borehole system**

Specific data of the borehole system are given below:


Ground-Source Heat Pumps and Energy Saving 471

Fig. 8. Schematic of the solar coupled to ground source heat pump system.

Fig. 9. Relevant temperatures for performed calculations.


To keep the borehole temperature at steady state between the years extracted and injected heat from/to the ground were balanced by charging solar heat during the summer.

#### **4.4 Solar collector**

Since the annual heating demand of the hangar is much greater than annual cooling demand, which mean the energy extracted from the ground will be more than that injected into the ground, recharging the borehole filed by external energy resource is need. The amount of available solar energy in Syria means great potential for combined solar and GSHP systems. The estimated required solar collector area without considering heat yield from ground was:

$$A = \frac{Q\_h \cdot (1 - \frac{1}{COP\_h}) - Q\_c \cdot (1 + \frac{1}{COPc})}{\eta \cdot \sigma} \tag{17}$$

Where


In this case, the required solar collector area was 85 m2. The solar heat is directly used when needed while the rest of the heat is stored to be used later (Fig.8).

#### **4.5 Operation**

During the wintertime Fig.8, water is pumped from the borehole through the solar collector to increase its temperature. The temperature increase, which is only 0.8 oC during the winter, is considerably greater during the summer. The heat pump cools the water before it is again pumped through the borehole, where it will be warmed up. The extracted heat is emitted into the hangar. Fig.9 shows that the lowest extracted water temperature from borehole is 11.5 oC. During summertime Fig.8, the ground temperature is cold enough for free cooling, so the water is pumped directly to the heat exchanger. Due to the heat exchange with indoor air, the water temperature will increase. After the heat exchanger, water passes though the solar collector and back to the borehole. Then, its temperature will decrease before pumped back to the hangar. Fig.9 shows that the highest extracted water temperature from borehole is 26.5 oC

To keep the borehole temperature at steady state between the years extracted and injected

Since the annual heating demand of the hangar is much greater than annual cooling demand, which mean the energy extracted from the ground will be more than that injected into the ground, recharging the borehole filed by external energy resource is need. The amount of available solar energy in Syria means great potential for combined solar and GSHP systems. The estimated required solar collector area without considering heat yield

> 1 1 1 1 *h c h Q( )Q( ) COP COPc <sup>A</sup> η σ*

(17)

In this case, the required solar collector area was 85 m2. The solar heat is directly used when

During the wintertime Fig.8, water is pumped from the borehole through the solar collector to increase its temperature. The temperature increase, which is only 0.8 oC during the winter, is considerably greater during the summer. The heat pump cools the water before it is again pumped through the borehole, where it will be warmed up. The extracted heat is emitted into the hangar. Fig.9 shows that the lowest extracted water temperature from borehole is 11.5 oC. During summertime Fig.8, the ground temperature is cold enough for free cooling, so the water is pumped directly to the heat exchanger. Due to the heat exchange with indoor air, the water temperature will increase. After the heat exchanger, water passes though the solar collector and back to the borehole. Then, its temperature will decrease before pumped back to the hangar. Fig.9 shows that the highest extracted water

heat from/to the ground were balanced by charging solar heat during the summer.

 Volumetric heat capacity: 2.16 MJ/m3.K Ground thermal conductivity: 3.5 W/m.K Drilling Configuration: open rectangle 175 (3 x 4)

 Borehole installation: Polyethylene U-pipe Fluid flow rate: 0.5 10-3 m3/s, borehole.

Borehole Spacing: 6 m.

**4.4 Solar collector** 

from ground was:

Qh Heating demand (MWh)

Qc Cooling demand (MWh)

temperature from borehole is 26.5 oC

COPh Coefficient of performance for heating (in this case =5)

 Yearly sun yield (in this case =1.973 MWh/m2) η Solar collector efficiency (in this case η=0.86).

COPc Coefficient of performance for free cooling (in this case =50)

needed while the rest of the heat is stored to be used later (Fig.8).

Where

**4.5 Operation** 

Fig. 8. Schematic of the solar coupled to ground source heat pump system.

Fig. 9. Relevant temperatures for performed calculations.

Ground-Source Heat Pumps and Energy Saving 473

Heating 1196 675 (COP=6.2) 1047 (COP=4) 2247 (η=0.85) 3479(η=0.85) Cooling 170 60 (COP=10) 138 (COP=4.3) 138 (COP=4.3) 138 (COP=4.3) Total 1366 735 1185 2385 3617

Table 3. Comparison between different heating/cooling systems for a typical chicken farm.

Energy GWh/y

GSHP 210 80.6

ASHP 338 130

with ASHP 1446 188.2

 The estimated installation cost of a borehole system for a typical chicken farm is \$15000. With current energy price in Syria the payback-time of GSHP is about 5.3, or 3 years compared to coal heater combined with ASHP, or diesel heater combined with ASHP,

The global energy oil production is unstable and will peak within a few years. Therefore, the energy prices are expected to rise and new energy systems are needed. In addition to this energy crisis the fossil fuels seems to be the main reason for climate change. There is a global political understanding that we need to replace fossil fuels by renewable energy systems in

About half of the global energy consumption is used for space heating and space cooling systems. Ground source heat pump systems are considered as an energy system that can make huge contributions to reduce energy consumption and thereby save the

System Required prime

ASHP 3.5 SP/kWh

SP/kWh 0.54 0.87 1.75 2.65

GSHP 3.5 SP/kWh Energy Cost (MSP)

Coal Heater 8,141 kWh/kg, 13 SP/kg

Required Coal (103 ton)

Diesel Heater 10,1 kWh/l 25 SP/L

Energy demand GWh/year

Energy Cost

Coal Heater

respectively.

**6. Conclusions** 

environment.

Table 4. comparison between the required prime energy.

order to develop a stable and sustainable energy supply.
