Homogeneous charge compression ignition (HCCI) is a form of internal combustion in which well-mixed fuel and oxidizer (typically air) are compressed to the point of auto-ignition. As in other forms of combustion, this exothermic reaction releases chemical energy into a sensible form that can be transformed in an engine into work and heat.
HCCI combines characteristics of conventional gasoline engine and diesel engines. Gasoline engines combine homogeneous charge (HC) with spark ignition (SI), abbreviated as HCSI. Diesel engines combine stratified charge (SC) with compression ignition (CI), abbreviated as SCCI.
As in HCSI, HCCI injects fuel during the intake stroke. However, rather than using an electric discharge (spark) to ignite a portion of the mixture, HCCI raises density and temperature by compression until the entire mixture reacts spontaneously.
Stratified charge compression ignition also relies on temperature and density increase resulting from compression. However, it injects fuel later, during the compression stroke. Combustion occurs at the boundary of the fuel and air, producing higher emissions, but allowing a leaner and higher compression burn, producing greater efficiency.
Talk to me baby, I'm listening
Lay down and tell me what's on your mind
What exactly did he do to make you cry this time
Well, I will be your comforter, I will make it right
He cast a shadow on your heart and I will bring back your light
Come in, I see he's hurt you again, when you are in pain, I'm in pain
That's part of being a friend but this is a special case
I held my feelings back because of him and now I can see it more than ever
I made a big big big, big mistake
I don't mean to disregard your feelings but I think that he's a fool
He don't know how sensitive you are and baby that just ain't cool
I'm just glad, I can be there for you when you need a helping hand
When deep inside my heart from the start I know I should've been your man
Lay down and tell me what's on your mind
What exactly did he do to make you cry this time
Well, I will be your comforter, I will make it right
He cast a shadow on your heart and I will bring back your light
I will comfort, comfort, comfort you
I will comfort, I will comfort you
I will comfort, comfort, comfort you
I will comfort, I will comfort you
I will comfort, comfort, comfort you
I will comfort, I will comfort you
I will comfort, comfort, comfort you
I will comfort, I will comfort you
Lay down and tell me what's on your mind
What exactly did he do to make you cry this time
Well, I will be your comforter, I will make it right