Exergoeconomic Analysis of a Novel Zeotropic Mixture Power System

N. Shankar Ganesh,Uma Maheswari,Tangellapalli Srinivas,B. V. Reddy 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.1

A parametric investigation of a novel ammonia water mixture power generation system is performed in this study. The overall performance and feasibility of the system of the proposed system are assessed from thermoeconomic, conventional exergy and advanced exergy perspectives. For better heat recovery in the existing medium-temperature heat recovery Kalina system, auxiliary solar heater is considered in the proposed design to improve the overall performance in terms of energy and exergy. The system performance parameters investigated include cycle efficiency, net output, total product cost rate, exergoeconomic factor and total exergy destruction rate. The simulation of the energy and exergy analysis was performed using Python coding. In this respect, the parametric investigation revealed that the cycle efficiency, net output, total product cost rate, exergoeconomic factor and total exergy destruction rate of the system at optimized conditions are 15.5%, 280 kW, 136 $/GJ, 66% and 120 kW, respectively. The irreversibilities of each component and overall system were evaluated and it was found that the turbine accounts for the highest exergy destruction among all components, contributing nearly 13% of the total exergy destruction of the system. Advanced exergy analysis was also performed that involved characterizing the exergy destruction as endogenous, exogenous, avoidable, and unavoidable, leading to specific recommendations for improving the performance of the system. Conventional exergy analysis suggests that the turbine, HE 4 , and separator are the components typically identified for improvement. The advanced exergy analysis in this study, however, indicated that the separator should be the primary focused for performance improvement, followed by the HE 4 and turbine.

Extended Exergy Analysis Based Comparison of Subcritical and Transcritical Refrigeration Systems

JAHAR SARKAR,Dnyanesh Joshi 대한설비공학회 2016 International Journal of Air-Conditioning and Refr Vol.24 No.2

The main purpose of this study is to apply advanced exergy analysis to the transcritical CO2 vapor compression refrigeration system, and compare with the analysis of subcritical cycle using ammonia and R404a. Endogenous, exogenous, avoidable and unavoidable exergy destructions are determined for each component of these systems. For CO2 system, compressor contributes highest avoidable endogenous exergy destruction and gas cooler contributes highest avoidable exogenous exergy destruction. It is concluded that compressor is the ¯rst component for CO2 and R404a, and evaporator is the ¯rst component for NH3 to be improved. System improvement options to reduce the exergy destruction are discussed as well.

외기조건에 따른 재생 증발식 냉각기를 이용한 제습 냉방시스템의 에너지 및 엑서지 해석

이장일(Jang-il Lee),변재기(Jae-ki Byun),남기훈(Ki-hoon Nam),최영돈(Young-don Choi),이대영(Dae-young Lee) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12

Desiccant cooling system is an air conditioning system that uses evaporative cooler to cool air and it can perform cooling by using heat energy only without electrically charged cooler. Thus, it can solve many problems of present cooling system including the destruction of ozone layer due to the use of CFC affiliated refrigerants and increase of peak power during summer season. In this study, exergy analysis was conducted in order to increase efficiency of desiccant cooling system. Using exergy analysis based on the second law of thermodynamics can resolve the issue related to system efficiency in a more fundamental way by analyzing the cause of exergy destruction both in whole system and each component. In addition, exergy analysis allows us to identify and quantify the sites with destruction of exergy. The purpose of this study is to evaluate COP, cooling capacity and exergy performance of desiccant cooling system in various outdoor air conditions.

Exergy destruction improvement of hydrogen liquefaction process considering variations in cooling water temperature

Lee Dong Hyeon,Yu Seo Yeon,Yeom Seung Yeol,Lee Jeong Jun,Kang Byeong Chan,Cho Chung Hun,Lee Seok Goo,Kim Yeonsoo 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.8

As the movement for carbon neutrality spreads around the world, research on hydrogen energy is also being actively conducted. In the hydrogen value chain, liquefaction is a particularly energy-intensive process. Although the operating energy of the hydrogen liquefaction process can vary greatly depending on the season or regional cooling water temperature, previous studies have not taken this into account. In this study, we quantitatively identify the effect of the change in cooling water temperature on exergy destruction, specific energy consumption (SEC), and coefficient of performance (COP) of the liquefaction process. In addition, we propose a design improvement to reduce exergy destruction with the exergy analysis of multi-stream heat exchangers. A new design (auxiliary process) that reduces exergy destruction is proposed by analyzing the device where energy destruction occurs the most. When the cooling water temperature increases from 20 °C to 35 °C, there is a tendency for SEC and exergy destruction to increase and the COP to decrease. The new design with an auxiliary process shows a decrease in SEC and a reduced rate of increase in SEC in response to the increase in cooling water temperature. The base case without the auxiliary cycle shows that the SEC with cooling water of 35 °C is 14.66% greater than that with cooling water of 20 °C, while the proposed process shows the rate of increase of 9.70%. This means that adding the auxiliary cycle can improve the energy efficiency and increase robustness to variations in ambient conditions.

Investigation of the thermodynamic performance of an existing steam power plant via energy and exergy analyses to restrain the environmental repercussions: A simulation study

Muhammad Haris Hamayun,Murid Hussain,Iqrash Shafiq,Ashfaq Ahmed,Young-Kwon Park 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.1

Exergy analysis is an important tool to identify the improvements in various industrial processes. In this study, the existing steam power plant is examined based on energy and exergy analyses. The steam network in the power plant is comprised of two sections, one of them is used for paddy drying, while other portion is used to operate the turbine for in-house electricity production. Mass, energy, and exergy balances are applied to individual equipment of the plant. The power plant is modeled and simulated using Aspen HYSYS® V10. The calculated thermodynamic values are used for in-depth analysis of the power plant. Case-studies are included in this study to show the effect of various operational parameters on the process efficiency. The analysis shows that the boiler is the major source of exergy destruction, because of the incomplete combustion process, and inappropriate insulations. The remedial actions are also suggested in the study.

Exergy characteristics of a ceiling-type residential air conditioning system operating under different climatic conditions

Arif Ozbek 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.11

In this study an energy and exergy analysis of a Ceiling-type residential air conditioning (CTRAC) system operating under different climatic conditions have been investigated for provinces within the different geographic regions of Turkey. Primarily, the hourly cooling load capacities of a sample building ( evap Q ɺ ) during the months of April, May, June, July, August and September were determined. The hourly total heat gain of the sample building was determined using the Hourly analysis program (HAP). The Coefficient of performance (COP), exergy efficiency (η) and exergy destruction ( dest Ex ɺ ) values for the whole system and for each component were obtained. The results showed that lower atmospheric temperature ( atm T ) influenced the performance of the system and each of its components.

Performance Enhancements in LiCl-H2O and LiBr-H2O Absorption Cooling Systems through an Advanced Exergetic Analysis

Parth Mody,Jatin Patel,Nishant Modi,Bhargav Pandya 대한설비공학회 2021 International Journal of Air-Conditioning and Refr Vol.29 No.1

This research study compares the thermodynamic performance of 10 kW lithium chloride–water (LiCl–H2O) and lithium bromide–water (LiBr–H2O) absorption cooling systems through first and second law of thermodynamics. Further, the exergy degradations happening in each component have been split into unavoidable and avoidable exergy degradations as well as endogenous and exogenous exergy degradations through advanced exergy analysis. Pressure–temperature–concentration (P–T –X) diagrams are drafted to clarify the real, ideal, and unavoidable cycles for LiCl–H2O and LiBr–H2O absorption cycles. Moreover, this paper exhibits the sensitivity of various system components towards the generator, condenser, and absorber temperature for both pairs. Energetic observation proves that LiCl–H2O pair is 10% more efficient as compared to LiBr–H2O pair. Exergetically, LiBr–H2O cycle struggles with additional (nearly 13.45%) exergy destruction than LiCl–H2O cycle. The major contribution (around 70% to 80%) of irreversibility comes from the generator and absorber. Comprehensively, the parametric partitions of irreversibility rate in each component provide broad indications to prioritize the system components for enhancements.

재생온도와 외기조건 변화에 따른 제습 냉방시스템의 냉방 성능 및 엑서지 해석에 관한 연구

이장일(Jang Il Lee),홍석민(Seok Min Hong),변재기(Jae Ki Byun),최영돈(Young Don Choi),이대영(Dae Young Lee) 대한기계학회 2014 大韓機械學會論文集B Vol.38 No.5

제습 냉방시스템은 증발식 냉각기를 이용하여 공조 공기를 냉각하는 시스템으로 전기구동 냉각기 없이 열에너지만으로 냉방 공급을 수행할 수 있다. 따라서, CFC 계열의 냉매 사용에 의한 오존층 파괴 및 하절기 냉각기 가동에 의한 첨두 전력부하의 증가 등 기존의 냉방시스템이 야기하는 여러 가지 문제점들을 해결할 수 있다. 본 연구에서는 제습 냉방시스템의 효율을 향상시키기 위해 냉방 성능과 엑서지 해석을 수행하였다. 특히 열역학 제2법칙에 근거한 엑서지 해석을 이용할 경우 전체시스템과 구성요소에서의 엑서지 파괴의 원인을 분석함으로써 시스템의 효율과 관련된 주제에 대하여 더욱 본질적인 측면에서 접근할 수 있다. 본 연구의 목적은 재생온도와 외기조건의 변화에 따른 재생 증발식 냉각기를 이용한 제습 냉방시스템의 성능계수, 냉방용량, 엑서지 성능을 평가하는 것이다. Desiccant cooling system is an air conditioning system that uses evaporative cooler to cool air and it can perform cooling by using heat energy only without electrically charged cooler. Thus, it can solve many problems of present cooling system including the destruction of ozone layer due to the use of CFC[chloro fluoro carbon] affiliated refrigerants and increase of peak power during summer season. In this study, cooling performance and exergy analysis was conducted in order to increase efficiency of desiccant cooling system. Especially, using exergy analysis based on the second law of thermodynamics can resolve the issue related to system efficiency in a more fundamental way by analyzing the cause of exergy destruction both in whole system and each component. The purpose of this study is to evaluate COP[coefficient of performance], cooling capacity and exergy performance of desiccant cooling system incorporating a regenerative evaporative cooler in various regeneration temperature and outdoor air conditions.

증기 분사 방식에 따른 가스터빈 시스템의 엑서지 해석

다시카,임석규,정영관,김경훈 한국수소및신에너지학회 2017 한국수소 및 신에너지학회논문집 Vol.28 No.5

Gas turbine system with steam injection has shown outstanding advantages such as high specific power and NOx reduction. In the present work, a comparative exergetic analysis was carried out for Steam Injected Gas Turbine (STIG), Regenerative Steam Injected Gas Turbine (RSTIG), and Regenerative After Fogging Gas Turbine (RAF). Effects of pressure ratio, steam injection ratio and steam injection method on the system performance was theoretically investigated. The results showed that the order of the highest exergy efficiency is RSTIG, RAF, and STIG for low pressure ratios but STIG, RSTIG, and RAF for high pressure ratios. In each arrangement, the combustion chamber has the highest exergy destruction and the compressor has the second one.

소형의 가스액화 공정에서 냉동시스템의 엑서지 해석

이춘식(Chun Sik Lee),이재용(Jae Yong Lee),김형진(Hyoung Jin Kim),박찬국(Chan Cook Park) 대한설비공학회 2011 대한설비공학회 학술발표대회논문집 Vol.2011 No.7

An exergy method is applied to analyze the low temperature refrigeration system using not only propane but also mixed refrigerant. these refrigeration cycle with two refrigerants is aimed to improve thermodynamic performance and specially fined in many plants for liquefied natural gas production. so in this work, small-scale liquefaction plant enabled to produce about 30kg liquefied natural gas per day is adopted for analysis of exergy destruction from all components of refrigeration system