How does a Turbocharger with Intercooler of Backhoe Loader Works?
Turbocharger: These are what are usually referred to as forced induction systems. Tur-bochargers compress the air flowing in the engine, meaning more oxygen rich air can be filled in the cylinder in addition to the fuel. This directly translates to more power without adding to the weight of the engine. Backhoe loaders are predominantly diesel engine meaning that the easier fuel requires more compressed cooled air for efficiency. The higher air requirement directly translates to a relatively larger turbocharger for diesel engines like that of a backhoe loader or any other heavy machinery.
Intercooler: An intercooler is basically an air intake device usually used with turbocharg-ers. The air compressed by the turbocharger gets very hot very fast so the intercooler is required to cool it and eventually increase the density of the air supplied to the en-gine.Every 10 degree drop in air temperature you gain a percent of horsepower, while every single increased psi translates to a three percent gain in horsepower. Now multiply and crunch the numbers to suit the specs of a backhoe loader and you will understand precisely how much of a difference an intercooler can make to your turbo charged engine. An intercooler can increase the output of a turbocharged engine by a whooping 10% if not more.
How they work together: When air is compressed in the turbocharger, it gets hot vey fast, meaning that it expands and the density of the air in the engine goes down along with the oxygen content. This is where the intercooler comes in. The intercooler cools down the compressed air thereby increasing the density and oxygen content of the air going into the engine. More oxygen means better combustion of the fuel translating to more power and better performance. This arrangement provides consistency in the temperature of the intake air so that the fuel to air ratio remains in a safe zone and steady.
There are usually two types of intercoolers
1. Air to air: This type of intercooler uses a network of tubes and cooling fins to cool the heated up compressed air. As the air is pushed through the intercooler, the heat is transferred to the tubes and cooling fins, while the cool air speeding in absorbs the heat thereby reducing the temperature of the compressed air. Lower cost, simplicity and light weight are its pro’s while relatively higher temperature fluctuations as com-pared to the air- water type is a con.
2. Air to water: This is a relatively bulkier arrangement since the heated water also re-quires cooling. In this type of an arrangement water is the agent used to transfer the heat from the compressed air. Cool water is pumped into the set up which absorbs the heat from the air as it passes through. The water is sent to cool in another coming cir-cuit while the compressed air goes to the turbocharger.
Diesel turbochargers may have one of the following avatars in your heavy machinery.
>Constant pressure system turbocharging: The benefits of this system include good performance even in high load. The cylinders do not require a grouping in multiples of 3, high turbine efficiency, 5-7% reduction in consumption of specific fuel oil in addition to smooth work transfer at the turbine wheel. The cons of this system is that the response to changing load is very poor.
>Pulse system of turbo charging: The system is highly efficient even at lower loads and speeds. It is independent of scavenger pumps and blower at any load change. The ar-rangement is highly responsive and efficient at all engine speeds both low and high. The acceleration of the turbocharger is also good. The few setbacks to this arrangement are a complicated exhaust grouping, various sizes of exhaust pipe spares are required and his pressure exhaust passing into another cylinder during low pressure scavenging effects the system’s combustion efficiency.
>Under piston pressure turbocharging: This is a type of constant pressure charging system with advantages like assistance in tangential swirl and complete evacuation of any remaining exhaust gases. Auxiliary blower may not be required during manoeuvring.
Each of these turbocharging systems have their own set of advantages and disadvantages that needs to be closely looked into before adopting either of these systems into a heavy machinery like the backhoe loader. OEM’s like Mahindra have spent in thousands of man-hours researching on which turbocharger system works best for their Earthmaster range of backhoe loaders. Depending on the design and engine of the backhoe loader either of the turbocharger intercooler systems can be installed as deemed fit by the OEM after exhaustive number crunching on their end