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In this study, the effects of critical operational constraints on the operational domain of a double-effect lithium bromide/water absorption refrigeration system and its performance were investigated. These constraints were determined as the equivalence state of concentrations, the thermal unbalance between the system components of high-pressure condenser and low-pressure generator, freezing and crystallization risk of lithium bromide/water solution. For the system analysis, a simulation program was developed, and its detailed solution procedure was presented. The program outputs were initially validated with the literature. Subsequently, parametric studies were conducted for broad ranges of the component temperatures. The results demonstrate that the considered constraints were essential for acceptable design and the operational control of double-effect absorption refrigeration systems. The simulations will help to figure out under which operating conditions a double-effect absorption refrigeration system functions effectively and what kind of control strategies are essentially required to increase the coefficient of performance. Based on the operation scenario of fixed high-pressure generator temperature, the proposed system can enhance the coefficient of performance up to 31% and 84% as compared to its counterparts which function under the variable high-pressure generator temperature and the pinch point temperature difference (5 K between the high-pressure condenser and the low-pressure generator), respectively. [ABSTRACT FROM AUTHOR]

Oil film on cylinder liner has been suggested as a major source of engine-out hydrocarbon emissions. In this study, a mathematical modeling for the rate of absorption/desorption of the fuel in the oil film has been developed for gasoline, LPG and methane. It was seen that the absorption/desorption mechanism of LPG and methane into the oil film were lower than gasoline. It was determined that the most dominant parameter of this difference was Henry's constant, which was related to solubility. As interaction time of oil film-fuel vapor was longer at low engine speeds, the quantities of HC absorbed/desorbed increased. The quantities of HC absorbed/desorbed increased with increasing inlet pressure and compression ratio. [ABSTRACT FROM AUTHOR]