## 3 Case Study--Description of Variants  
### Basic Solution--Variant 0  
The total cooling power of the cooling energy receivers installed in the studied pharmaceutical plant amounted to 4600 kW. The total cooling power of the cooling energy sources present in the facility equaled 3635 kW, which constituted 78% of the total cooling power of all receivers. The entire amount of the 7/15 \({}^{\circ}\)C chilling water produced in the plant was used for cooling and drying the air in the air conditioning systems in the technological area and for cooling the air in the office area and auxiliary production area (i.e., control rooms, server rooms, CCTV rooms).  
The planned development and modernization of the chilling water production system assumed an increase of cooling power to 4085 kW, with the technological structure of the source to be as follows:  
* CHCh1--compression chiller with in-built condenser; planned chiller with 1000 kW cooling power (EER = 3.03, SEER = 3.85),
* CWCh3--compression chiller; existing chiller with 635 kW cooling power,
* CWCh4--compression chiller with in-built condenser; planned chiller with 650 kW cooling power (EER = 2.99, SEER = 3.85),
* CWCh5--compression chiller; existing chiller with 900 kW cooling power,
* CWCh6--compression chiller; existing chiller with 900 kW cooling power  
Each of the above-listed chillers was connected to a joint 2 xDn350 chilling water collector via an individual pipe connection equipped with a hydraulic control system, i.e., a set of throttles. Said collector powered a hydraulic loop supplying chilling water to all receivers located in the facility.  
An additional element of the planned modernization of the plant's cooling source was a free cooling system equipped with two dry air coolers, DC1 and DC2, with 1200 kW maximum cooling power (operating with external temperatures below 0 \({}^{\circ}\)C).  
A schematic of the basic solution (Variant 0) for chilled water system retrofitting is shown in Figure 2.  
The planned modernization of the chilled water production system in the facility did not change the cooling economy there. The economy was still meant to be based on compression water chillers powered by electricity. In addition, the chillers used, with integrated air-cooled condensers, had relatively low EERs and SEERs. Consequently, one would expect a slight drop in the consumption of primary energy and a small drop in the carbon dioxide emissions of the plant.  
However, this situation could change by using dual-stage, steam-powered absorption water chillers (AWChs). The source of power of a dual-stage AWCh is high pressure steam.  
The facility under study is equipped with a natural-gas fueled, back-pressure combined heat and power plant. The total production capacity for 10 bar steam is 9.6 Mg/h, with 6.4 Mg/h being used continuously by the facility for technological purposes. The remaining steam production capacity of the CHP plant (3.2 Mg/h) is a reserve that can be used to power dual-stage absorption water chillers.  
The average annual energy efficiency of the CHP plant (production and transmission) is \(\eta_{\mathrm{EC}}\) = 0.875, and the average annual heat production co-generation ratio in the form of steam and electricity \(e\) = 0.41.  
Based on the verified balance of cooling needs and the proposed scenario for chilled water source modernization, two variants of cooling energy supply to the facility were proposed, employing dual-stage, absorption water chillers--Variants 1 and 2. Both variants involved the installation of new water chillers with total cooling capacity of 1650 kW.