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A modified Kalina cycle with parallel cogeneration of power and refrigeration abbreviated as PPR-KC was proposed and investigated. The cycle cogenerates refrigeration by further reclaiming heat resource from the boiler. A parallel branch of work solution is split at the outlet of the mid-p-absorber, and it undergoes pumping, generation, rectification and condensation before evaporation for refrigeration. Then the vapor from the evaporator goes to a mixer at the low-p-absorber inlet via a subcooler, while the dilute solution from the generator heats the basic solution in the second recuperator before going to the mixer via a throttle valve. The split fraction which determines the relative percentage of work solution flow rate for power generation or refrigeration can be altered arbitrary at user’s demand. The parameter optimization was conducted and the optimum work concentration is 0.5 and the optimum basic concentration shall be adjusted with different split fraction. Under temperatures of heat resource/cooling water are 400 °C/30 °C and minimum pinch temperature differences in heat exchangers with/without flue gas are 20/5 K respectively, the comprehensive power recovery efficiency of the PPR-KC reaches 27.2%, which is 9.85% and 20.24% respectively higher than those of the cogeneration cycle proposed by Liu et al. and the Kalina cycle. [ABSTRACT FROM AUTHOR]

The integrated system of AWKRC (ammonia–water Kalina–Rankine cycle) is a novel cycle operated on KC (Kalina cycle) for power generation in non-heating seasons and on AWRC (ammonia–water Rankine cycle) for cogeneration of power and heating water in winter. The influences of inlet temperatures of both heat resource and cooling water on system efficiencies were analyzed based on the first law and the second law of thermodynamics. The calculation is based on following conditions that the heat resource temperature keeps 300 °C, the cooling water temperature for the KC or AWRC is respectively 25 °C or 15 °C; and the temperatures of heating water and backwater are respectively 90 °C and 40 °C. The results show that the evaluation indexes of the power recovery efficiency and the exergy efficiency of KC were respectively 18.2% and 41.9%, while the composite power recovery efficiency and the composite exergy efficiency of AWRC are respectively 21.1% and 43.0% accounting both power and equivalent power of cogenerated heating capacity, including 54.5% heating recovery ratio or 12.4% heating water exergy efficiency. The inventory flow diagrams of both energy and exergy gains and losses of the components operating on KC or AWRC are also demonstrated. [ABSTRACT FROM AUTHOR]

• Kalina cycle based power/refrigeration cogeneration cycle (PPRAT-KC) was studied. • Adjustable range of refrigeration temperature is about from -22℃ to 7.5℃. • Adjustment of refrigeration temperature has no effect on amounts of energy outputs. • Amount of net power or refrigeration energy output can be flexibly adjusted. • The PPRAT-KC can maintain high performance when altering refrigeration temperature. Two schemes of power and refrigeration cogeneration Kalina cycle with adjustable refrigeration temperature (PPRAT-KC) based on the efficient cogeneration cycle PPR-KC are proposed and studied. In the PPRAT-KC, the refrigerant vapor is absorbed in a pressure adjustment absorber with dilute solution either from the separator or the low-pressure pump, and by altering the flow rate of the dilute solution, the refrigeration temperature is able to be adjusted with nearly no effect on the amounts of energy outputs. The amount of net power or refrigeration capacity in the PPRAT-KC can be also adjusted by changing the flow rate of solutions fed to the power and refrigeration sub-cycles. Under temperatures of heat source and cooling water of 400℃ and 30℃, respectively, the change range of refrigeration temperature for the two schemes of the PPRAT-KC are about from -22℃ to 7.5℃, and the performances of the two schemes are similar. With the same work concentration of 0.5 and refrigeration temperature of -15℃, the effective exergy effeciency of PPRAT-KC is 0.5653, which is 4.145% and 10.97% higher than those of the PPR-KC and the triple pressure Kalina cycle, respectively. [ABSTRACT FROM AUTHOR]

• Air conditioning refrigeration achieves by guiding refrigerant vapor to mid-absorber. • Parallel PR cogeneration KC matches heat source well in cascade boiler and generator. • Leading generator dilute solution to low-pressure absorber has better performance. • Performances are improved by optimizing solution concentrations and boiler superheat. • Refrigeration/power ratio extends to 1.192 with boiler bubble point Δ t rises to 60 K. A parallel power/refrigeration cogeneration Kalina cycle (PPR-KC) system with adjustable refrigeration/power ratio that developed on the basis of the triple-pressure Kalina cycle system was analyzed. The PPR-KC system can produce refrigeration with temperature ranging in either air conditioning or ice making by switching the exhaust refrigerant vapor to the mid-pressure absorber or to the low-pressure one. The influences of the dilute solution from generator to the destination of either mid-pressure absorber (plan A) or low-pressure absorber (plan B) via recuperators on the performances of the PPR-KC system for air conditioning were investigated. The results show that the PPR-KC system matches well the heat source in cascade arranged boiler and generator thus showing excellent thermal performance by optimizing the solution concentrations, boiler superheat and other parameters. Under the given temperatures of heat source 400°C and cooling water 30°C respectively, the variation trends of the cycle parameters and performances of both plan A and plan B are presented. The power recovery efficiency of plan B is about 1.6% higher than that of plan A. When boiler bubble point temperature difference increases from 20 K to 60 K the refrigeration/power ratio of plan B climbs from 0.475 to 1.192. [ABSTRACT FROM AUTHOR]

A modified dual-pressure vaporization Kalina cycle (DPV–KC2) is proposed with the second evaporator installed parallel to the economizer and both are in series after the first evaporator. The merit is to acquire higher efficiency by reduced thermal irreversibility in heat transfer between heat source and working medium. The parameter optimizations were conducted with power recovery efficiency as the cycle performance evaluation index. The calculation conditions are set as that the inlet temperatures of heat source and cooling water are 400 °C and 25 °C respectively with the constraints such as heat transfer pinch point temperature differences are proper, the maximum evaporation pressure does not exceed 20 MPa, the vapor quality at the turbine outlet is greater than 0.85 and the exhaust temperature of heat source is not lower than 90 °C. The optimal parameters obtained include concentrations of work solution and basic solution of 0.5 and 0.3138 respectively, the evaporation dew point temperature of 300 °C, the supercool at outlet of economizer of 5 K and the superheating at the second evaporator outlet of 75 K respectively. And the corresponding power recovery efficiency of the DPV–KC2 reaches 26.4%, which is 3.4% and 15.2% respectively higher than that of the DPV–KC and the Kalina cycle. [ABSTRACT FROM AUTHOR]

To further improve the cycle efficiency with the heat transfer curves between higher than 350 °C heat resource and the evaporating working medium of the Kalina cycle and to reduce the exhaust temperature of heat resource, the dual-pressure vaporization Kalina cycle for cascade utilization of high-to-mid grade heat resource is proposed. The optimization was conducted for parameters in this modified Kalina cycle such as concentrations of work solution and basic solution, evaporation dew point temperature. Under the conditions of inlet temperatures of heat resource and cooling water of respectively 400 °C and 25 °C and the constraints of proper heat transfer pinch point temperature differences, the maximum evaporation pressure not exceeds 20 MPa, the vapour quality at the turbine outlet is greater than 0.85 and the exhaust temperature of heat resource is not lower than 90 °C, the optimum parameters are obtained that the work and basic concentrations are 0.45 and 0.272 respectively, the dew point temperature of evaporation is 300 °C, and the corresponding power recovery efficiency of the dual-pressure vaporization Kalina cycle reaches 27%, which is 17% higher than that of the Kalina cycle with optimum parameters. [ABSTRACT FROM AUTHOR]

An integrated system of ammonia–water Kalina–Rankine cycle (AWKRC) for power generation and heating is introduced. The Kalina cycle has large temperature difference during evaporation and small one during condensation therefore with high thermal efficiency for power generation, while the ammonia–water Rankine cycle has large temperature difference during condensation as well as evaporation, thus it can be adopted to generate heating-water as a by-product in winter. The integrated system is based on the Kalina cycle and converted to the Rankine cycle with a set of valves. The performances of the AWKRC system in different seasons with corresponding cycle loops were studied and analyzed. When the temperatures of waste heat and cooling water are 300 °C and 25 °C respectively, the thermal efficiency and power recovery efficiency of Kalina cycle are 20.9% and 17.4% respectively in the non-heating seasons, while these efficiencies of the ammonia–water Rankine cycle are 17.1% and 13.1% respectively with additional 55.3% heating recovery ratio or with comprehensive efficiency 23.7% higher than that of the Kalina cycle in heating season. [ABSTRACT FROM AUTHOR]