Dew point refrigeration systems: Normalized sensitivity analysis and impact of fouling

Compressed natural gas is transmitted through a network of pipelines after its production from oil-gas wells. This gas is then cooled below the dew-point to remove the condensate that may accumulate in the transmission line, causing erosion and deposits. In this paper, the dew-point refrigeration system used with a gas compression system is investigated. The design conditions are obtained from the manufacturer data sheets, which are validated with a computer program to study both the design and rating of such systems. The coefficient of performance (COP) of the system at the design condition is 2.81, while the effectiveness of condenser is 0.84 and that of evaporator is 0.91. The system COP sensitivity with regard to inlet single-phase temperatures, superheat temperature and conductance of heat exchangers (UA), is examined. It is found that the system is more sensitive under design conditions as compared to performance operations. The effect of fouling that degrades the UA value of the condenser and evaporator is also studied. It is found that condenser fouling has a significant impact on the performance of the system. The impact of alternate refrigerants at optimized intermediate pressure, is also investigated.