# Impact of Heat Exchanger Effectiveness and EGR on Energy and Emission Performance of a CI Engine
## 2 Materials and Methods  
### Methodology of Experimental Research  
The experimental investigation was carried out using a four-cylinder turbocharged direct injection CI engine 1Z with a displacement of 1896 cm3 (Volkswagen AG, Wolfsburg, Germany). A schematic diagram of the experimental test bench is shown in Figure 1. The engine was equipped with a BOSCH VP37 (Robert Bosch Ltd., Gerlingen, Germany) rotary distributor-type high-pressure fuel injection pump. Fuel injection timing (start of injection) is electronically controlled by the engine's Electronic Control Unit (ECU) through management of the high-pressure pump. Fuel is delivered via a single-injection process using a two-stage injector fitted with a dual-spring needle assembly: the primary spring enables a low-pressure pilot injection, while the secondary spring allows full needle lift for the main injection at higher pressure. This staged injection strategy improves combustion efficiency and reduces emissions. The VW 1.9 CI engine employs open-loop ECU control for both the EGR and turbocharger systems. EGR flow is regulated based on predefined maps and intake air mass estimation, without closed-loop feedback. Boost control relies on a wastewater actuator, which limits the maximum turbocharger pressure according to ECU commands, also without real-time correction. Detailed technical engine specifications are provided in Table 1. The ICE was cooled using a common coolant circulation system. Experimental investigations were conducted using a KI-5543 electric engine test bench (Gosniti Rosselhozakademii, Moscow, Russia), equipped with a lever-arm dynamometer for measuring engine torque, with measurement uncertainty \(\pm\)1.23 Nm. Figure 1: Schematic diagram of the experimental test bench: 1—1.9 CI engine; 2—high-pressure fuel pump; 3—turbocharger; 4—EGR valve; 5—heat exchanger (intercooler); 6—connecting shaft; 7—engine load unit; 8—engine load indicator; 9—fuel injection timing sensor; 10—in-cylinder pressure sensor; 11—intake air temperature sensor; 12—boost pressure sensor; 13—exhaust gas temperature sensor; 14—smoke meter; 15—intake gas temperature sensor; 16—mass air flow meter; 17—exhaust gas analyzer; 18—in-cylinder pressure acquisition system; 19—fuel scale; 20—fuel tank; 21—crankshaft position sensor; 22—coolant tank; 23—type-K thermocouple; 24—coolant pump; 25—fuel injection timing control system. Fuel consumption was measured using SK-5000 electronic scales (A&D Company, Limited, Tokyo, Japan) and a stopwatch, with a relative measurement error of 0.5%. The intake air mass flow rate (kg/h) was determined using a BOSCH HFM 5 air mass meter (Robert Bosch Ltd., Abstatt, Germany) with an accuracy of 2%. The boost pressure generated by the turbocharger was measured using a Delta OHM HD 2304.0 manometer (Senseca Italy SrI, Caselle, Italy), with a measurement uncertainty of \(\pm\)0.002 bar. In-cylinder pressure was also recorded during each test using an AVL GH13P pressure sensor (AVL DiTEST GmbH, Graz, Austria) installed in place of the glow plug. The exhaust gas components were measured using the AVL DiCom 4000 gas analyzer (AVL DiTEST GmbH, Graz, Austria), the technical specifications of which are presented in Table 2.  
A liquid-cooled heat exchanger from a Subaru Impreza 2.0T vehicle was installed in the engine air intake system (Figure 2). The heat exchanger is equipped with air inlet (1) and outlet (2) ports, as well as coolant inlet and outlet ports (3). A screw cap (4) is used for filling the coolant and for removing air locks from the heat exchanger's cooling circuit. During the experimental investigation, the HEE of the heat exchanger was varied by adjusting the flow rate of coolant (water) through the heat exchanger.