Experimental Results of an Ammonia-Water Mixture Turbine System: Effectiveness With a Low Temperature Heat Source

Author(s):  
Keisuke Takeshita ◽  
Kouji Morimoto ◽  
Yoshiharu Amano ◽  
Takumi Hashizume

This paper presents an experimental investigation of the effectiveness of an AWM (Ammonia-Water Mixture) turbine system with low temperature heat sources. The AWM turbine system (AWMTS) features Kalina cycle technology, namely, it employs an ammonia-water mixture as the working fluid and includes a separation / absorption process of NH3-H2O. Since AWM is a non-azeotropic mixture, its temperature changes during evaporation and condensation. This behavior gives AWMTS the advantage of heat recovery from a sensible heat source such as exhaust gas. It is known that an AWMTS can generate more power than a Rankine cycle system from 250–650°C sensible heat sources. The authors constructed a 70 KW-experimental facility and investigated the practical applications of AWMTS. It is located at the bottoming stage below a conventional combined cycle composed of a gas turbine and a steam turbine. Its heat source is the exhaust steam from a back pressure steam turbine at the middle stage of the system. The experiment was carried out with changing the back pressure of the steam turbine. The experimental results show that power generation is possible from 138 to 162 °C heat source steam.


2004 ◽  
Vol 2004.3 (0) ◽  
pp. 277-278
Author(s):  
Keisuke TAKESHITA ◽  
Koji MORIMOTO ◽  
Yoshiharu AMANO ◽  
Takumi HASHIZUME


Author(s):  
Yoshiharu Amano ◽  
Keisuke Kawanishi ◽  
Takumi Hashizume

This paper reports results from experimental investigations of the dynamics of an ammonia-water mixture turbine system. The mixture turbine system features Kalina Cycle technology [1]. The working fluid is an ammonia-water mixture (AWM), which enhances the power production recovered from the low-temperature heat source [2], [3]. The Kalina Cycle is superior to the Rankine Cycle for a low temperature heat source [4], [5]. The ammonia-water mixture turbine system has distillation-condensation processes. The subsystem produces ammonia-rich vapor and a lean solution at the separator, and the vapor and the solution converge at the condenser. The mass balance of ammonia and water is maintained by a level control at the separator and reservoirs at the condensers. Since the ammonia mass fraction in the cycle has a high sensitivity to the evaporation/condensation pressure and vapor flow rate in the cycle, the pressure change gives rise to a flow rate change and then level changes in the separators and reservoirs and vice versa. From the experimental investigation of the ammonia-water mixture turbine system, it was observed that the sensitivity of the evaporating flow rate and solution liquid density in the cycle is very high, and those sensitivity factors are affected by the ammonia-mass fraction. This paper presents the experimental results of a study on the dynamics of the distillation process of the ammonia-water mixture turbine system and uses the results of investigation to explain the mechanism of the unstable fluctuation in the system.



Author(s):  
Keisuke Takeshita ◽  
Yoshiharu Amano ◽  
Takumi Hashizume ◽  
Akira Usui ◽  
Yoshiaki Tanzawa

This paper is an additional report to the paper by Amano (2001). In this paper, the authors report the additional experimental results of the effect of an ammonia mass fraction at the inlet of the AWM (Ammonia-Water Mixture) vapor generator in the AWM turbine system. The AWM turbine system features the Kalina Cycle technology. The 70KW-experimental facility was built in order to gain knowledge for practical applications. The heat source is the exhaust steam from a back-pressure steam turbine. The AWM turbine system is installed at the bottoming stage of a combined cycle which has a gas turbine, a steam turbine and an AWM turbine for cascade utilization of heat. The authors designed and constructed an experimental facility, the ACGS (the Advanced Co-Generation System), to investigate various energy-saving technologies for a distributed energy supply system in the Advanced Research Institute for Science and Engineering at Waseda University. One of the main targets is a hybrid combined heat and power supply system that uses AWM as its working fluid. The AWM turbine system was developed for the bottoming stage of a “trinary turbine cycle system” which is composed of a gas turbine, a steam turbine and the AWM turbine systems. The experimental results of the ammonia mass fraction to the cycle efficiency are investigated with a range of the ammonia mass fraction between 0.4 [NH3kg/kg] to 0.7 [NH3kg/kg]. It shows that there are optimal operating conditions depending on the heat source temperature with an ammonia mass fraction of the cycle. The simulation model of the AWM turbine system shows good agreement with the experimental data.



Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1853 ◽  
Author(s):  
Pavel Neuberger ◽  
Radomír Adamovský

The efficiency of a heat pump energy system is significantly influenced by its low-temperature heat source. This paper presents the results of operational monitoring, analysis and comparison of heat transfer fluid temperatures, outputs and extracted energies at the most widely used low temperature heat sources within 218 days of a heating period. The monitoring involved horizontal ground heat exchangers (HGHEs) of linear and Slinky type, vertical ground heat exchangers (VGHEs) with single and double U-tube exchanger as well as the ambient air. The results of the verification indicated that it was not possible to specify clearly the most advantageous low-temperature heat source that meets the requirements of the efficiency of the heat pump operation. The highest average heat transfer fluid temperatures were achieved at linear HGHE (8.13 ± 4.50 °C) and double U-tube VGHE (8.13 ± 3.12 °C). The highest average specific heat output 59.97 ± 41.80 W/m2 and specific energy extracted from the ground mass 2723.40 ± 1785.58 kJ/m2·day were recorded at single U-tube VGHE. The lowest thermal resistance value of 0.07 K·m2/W, specifying the efficiency of the heat transfer process between the ground mass and the heat transfer fluid, was monitored at linear HGHE. The use of ambient air as a low-temperature heat pump source was considered to be the least advantageous in terms of its temperature parameters.



2019 ◽  
Vol 27 (02) ◽  
pp. 1950012 ◽  
Author(s):  
Zeynab Seyfouri ◽  
Mehran Ameri ◽  
Mozaffar Ali Mehrabian

In the present study, a totally heat-driven refrigeration system is proposed and thermodynamically analyzed. This system uses a low-temperature heat source such as geothermal energy or solar energy to produce cooling at freezing temperatures. The proposed system comprises a Rankine cycle (RC) and a hybrid GAX (HGAX) refrigeration cycle, in which the RC provides the power requirement of the HGAX cycle. An ammonia–water mixture is used in both RC and HGAX cycles as the working fluid. A comparative study is conducted in which the proposed system is compared with two other systems using GAX cycle and/or a single stage cycle, as the refrigeration cycle. The study shows that the proposed system is preferred to produce cooling at temperatures from 2∘C to [Formula: see text]C. A detailed parametric analysis of the proposed system is carried out. The results of the analysis show that the system can produce cooling at [Formula: see text]C using a low-temperature heat source at 133.5∘C with the exergy efficiency of about 20% without any input power. By increasing the heat source temperature to 160∘C, an exergy efficiency of 25% can be achieved.



Author(s):  
Martina Leveni ◽  
Arun Kumar Narasimhan ◽  
Eydhah Almatrafi ◽  
D. Yogi Goswami

Abstract Low temperature heat sources inherently result in lower cycle efficiencies, which can be improved by means of combined power and cooling generation. In order to produce power and cooling, appropriate thermodynamic cycles and working fluids must be used. Goswami cycle is a combined cycle that produces power and refrigeration by using ammonia-water mixture for low temperature heat sources. In the present study, a scroll expander is modeled specifically for the cycle operating conditions and a theoretical investigation is conducted to determine the cycle performance. A scroll expander design suitable for the operating conditions improves the power output and thereby overall thermal efficiency. The scroll expander efficiency varied between 0.05 and 0.61 for the pressure ratio between 2.2 and 8.6, with a maximum efficiency of 0.697 achieved at a pressure ratio of about 4.4. An internal heat recovery from the rectifier is proposed along with a flow split in the strong solution and analyzed for overall cycle energy efficiency improvement. Internal heat recovery from the rectifier increased the first law effective efficiency and the effective exergy efficiency by 7.9% and 7.8%, respectively, over the basic configuration.



Author(s):  
D. Y. Goswami ◽  
Gunnar Tamm ◽  
Sanjay Vijayaraghavan

A new thermodynamic cycle has been developed for the simultaneous production of power and cooling from low temperature heat sources. The proposed cycle combines the Rankine and absorption refrigeration cycles, providing power and cooling in desired ratios to best suit the application. A binary mixture of ammonia and water is used as the working fluid, providing a good thermal match with the sensible heat source over a range of boiling temperatures. Due to its low boiling point, the ammonia-rich vapor expands to refrigeration temperatures while work is extracted through the turbine. Absorption condensation of the vapor back into the bulk solution occurs near ambient temperatures. The proposed cycle is suitable as a bottoming cycle using waste heat from conventional power generation systems, or can utilize low temperature solar or geothermal renewable resources. The cycle can be scaled to residential, commercial or industrial uses, providing power as the primary goal while satisfying some of the cooling requirements of the application. The cycle is under both theoretical and experimental investigations. Initial parametric studies of how the cycle performs at various operating conditions showed the potential for the cycle to be optimized. Optimization studies performed over a range of heat source and heat sink temperatures showed that the cycle could be optimized for maximum work or cooling output, or for first or second law efficiencies. Depending on the heat source temperatures, as much as half of the output may be obtained as refrigeration under optimized conditions, with refrigeration temperatures as low as 205 K being achievable. Maximum second law efficiencies over 60% have been found with the heat source between 350 and 450 K. An experimental system was constructed to verify the theoretical results and to demonstrate the feasibility of the cycle. The investigation focused on the vapor generation and absorption processes, setting up for the power and refrigeration studies to come later. The turbine was simulated with an equivalent expansion process in this initial phase of testing. Results showed that the vapor generation and absorption processes work experimentally, over a range of operating conditions and in simulating the sources and sinks of interest. The potential for combined work and cooling output was evidenced in operating the system. Comparison to ideally simulated results verified that there are thermal and flow losses present, which were assessed to make both improvements in the experimental system and modifications in the simulations to include realistic losses.



2009 ◽  
Vol 13 (4) ◽  
pp. 21-31 ◽  
Author(s):  
Periklis Lolos ◽  
Emanuil Rogdakis

In this paper the operation of a reversible Kalina power cycle driven by low temperature heat sources has been studied. A numerical model has been developed to analyze thermodynamically the proposed cycle and to represent it in temperature-entropy and temperature-enthalpy diagrams. A parametric study has been conducted in order to specify the optimum values of the main parameters, i. e. low pressure, condensation and heat source temperature with respect to thermal performance. An improved configuration using a counter-current absorber instead of the conventional condenser (co-current absorber) has been proposed which has significantly higher efficiency and work output. Finally, simple equations have been derived which link the main parameters of the unit with the theoretical thermal efficiency.



2005 ◽  
Vol 2005.3 (0) ◽  
pp. 313-314
Author(s):  
Keisuke TAKESHITA ◽  
Akinori NAGASHIMA ◽  
Yoshiharu AMANO ◽  
Takumi HASHIZUME




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