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Scrubbers are more and more used to recover waste heat from coal-fired exhaust flue gas (EFG). But the heat and mass transfer mechanism in the counter flow direct contact scrubber is not clear enough, and the heat recovery rate (E) needs to be improved cost effectively. This paper proposes to use a simulation model to study the heat and mass transfer mechanism and thus to improve the scrubber design without intensive experiments. A mathematical model based on the two-film theory was established, and the finite difference method was used to solve it. The model was validated using experimental data and heat recovery equation is obtained with relation to the main influencing factors. The results show that the most sensitive factors on E are the liquid-to-gas ratio rwf and the equivalent diameter of water droplets rd. In addition, height to diameter ratio (H/D) is more important than flue gas velocity. E can be increased by 25 % and 36 % when rwf increases from 4 to 6 and rd decreases from 0.002 m to 0.0015 m, respectively. Intensive simulations help determine the scope of the influencing factors to improve scrubber design.
Haichao Wang; Xiaozhou Wu; Zheyi Liu; Katja Granlund; Risto Lahdelma; Ji Li; Esa Teppo; Li Yu; Lin Duamu; Xiangli Li; Ilkka Haavisto. Waste heat recovery mechanism for coal-fired flue gas in a counter-flow direct contact scrubber. Energy 2021, 121531 .
AMA StyleHaichao Wang, Xiaozhou Wu, Zheyi Liu, Katja Granlund, Risto Lahdelma, Ji Li, Esa Teppo, Li Yu, Lin Duamu, Xiangli Li, Ilkka Haavisto. Waste heat recovery mechanism for coal-fired flue gas in a counter-flow direct contact scrubber. Energy. 2021; ():121531.
Chicago/Turabian StyleHaichao Wang; Xiaozhou Wu; Zheyi Liu; Katja Granlund; Risto Lahdelma; Ji Li; Esa Teppo; Li Yu; Lin Duamu; Xiangli Li; Ilkka Haavisto. 2021. "Waste heat recovery mechanism for coal-fired flue gas in a counter-flow direct contact scrubber." Energy , no. : 121531.
Key stakeholders in industry are highly responsible for achieving energy performance targets. Particularly, this paper assesses the attitudes, approaches, and experiences of Finnish construction professionals regarding energy-efficient buildings, or nZEBs. A three-tier investigation was conducted including surveys and expert interviews with several stakeholders. The structure of this approach was informed by preliminary data and information available on the Finnish construction sector. The questionnaire showed that the stakeholders ranked energy efficiency and embodied energy/carbon as very important. The survey highlighted that the importance of the embodied carbon CO2 in the materials is less important than the energy efficiency from many of the stakeholders’ points of view. “Energy efficiency” is very important for ESCOs, contractors, and facility managers followed by architects, HVAC engineers, and construction design engineers. Nevertheless, the opinions of architects ranked “embodied energy CO2” as the most important regarding nZEB. When it comes to the importance of “running time emissions” toward nZEB, contractors and ESCO companies ranked it as 1 for importance followed by property owners (78%) and tenants (75%). It is very fascinating to see from the survey that “running time carbon emissions” has been ranked 1 (very important) by all stakeholders. This study will enable construction industry stakeholders to make provisions for overcoming the barriers, gaps, and challenges identified in the practices of the nZEB projects. It will also inform the formulation of policies that drive retrofit uptake.
Sadaf Alam; Miimu Airaksinen; Risto Lahdelma. Attitudes and Approaches of Finnish Retrofit Industry Stakeholders toward Achieving Nearly Zero-Energy Buildings. Sustainability 2021, 13, 7359 .
AMA StyleSadaf Alam, Miimu Airaksinen, Risto Lahdelma. Attitudes and Approaches of Finnish Retrofit Industry Stakeholders toward Achieving Nearly Zero-Energy Buildings. Sustainability. 2021; 13 (13):7359.
Chicago/Turabian StyleSadaf Alam; Miimu Airaksinen; Risto Lahdelma. 2021. "Attitudes and Approaches of Finnish Retrofit Industry Stakeholders toward Achieving Nearly Zero-Energy Buildings." Sustainability 13, no. 13: 7359.
This study proposes to use gas-fired boilers as peak shaving heat sources in heating substations due to their capability to increase the reliability, flexibility and heat capacity without the need to change the district heating network (DHN). However, the design and operational requirements with different connection modes for this kind of DH system are still not clear. This paper presents a systematic study on this kind of DH system, analyzes the connection modes of series and parallel connections between the gas-fired boilers and the heat exchangers. For each connection mode, we figured out the thermal balances and obtained the design and operational parameters including the supply temperatures of the heat exchangers, gas-fired boilers and their variations under different network temperature levels and the base load ratios (β). Under the series connection mode, the design supply temperature of the heat exchangers has no relation with the design peak shaving flow ratio (ω’); it decreases linearly along with smaller β, and the decreasing slope is higher with bigger temperature difference (Δt) of the DHN. However, the design supply temperatures of gas-fired boilers increase linearly when β and/or ω’ are smaller, and the increasing speed is proportional to Δt. For the parallel connection mode, the design supply temperatures of the heat exchangers and gas-fired boilers are all affected by β, ω’ and Δt. The former decreases when β and/or ω’ are smaller, while the latter increases at the same time. Finally, the design peak shaving flow ratio ω’ are determined for the peak boilers with series and parallel connection modes. The study provides a theoretical basis for the design and operation of the DH system with peak heating boilers in substations in order to reach a lower investment and higher efficiency.
Xiangli Li; Haichao Wang; Xiaozhou Wu; Lin Duanmu; Esa Teppo; Risto Lahdelma; Ji Li; Li Yu. Analysis on the Thermal Balance and Operational Parameters for the District Heating System with Peak Load Boilers in Heating Substations. Energies 2020, 13, 6180 .
AMA StyleXiangli Li, Haichao Wang, Xiaozhou Wu, Lin Duanmu, Esa Teppo, Risto Lahdelma, Ji Li, Li Yu. Analysis on the Thermal Balance and Operational Parameters for the District Heating System with Peak Load Boilers in Heating Substations. Energies. 2020; 13 (23):6180.
Chicago/Turabian StyleXiangli Li; Haichao Wang; Xiaozhou Wu; Lin Duanmu; Esa Teppo; Risto Lahdelma; Ji Li; Li Yu. 2020. "Analysis on the Thermal Balance and Operational Parameters for the District Heating System with Peak Load Boilers in Heating Substations." Energies 13, no. 23: 6180.
To achieve efficient transition towards climate and energy framework targets, improvement in energy efficiency is important. This paper presents a model for long-term multi-area combined heat and power production with heat and power storages, and power transmission between areas. Assuming fixed unit commitment, the model minimizes total production and transmission cost. The model can in principle be solved as a linear programming model. However, energy storages impose dynamic constraints to the model, making the long-term model very large and slow to solve. To speed up solution and to allow larger models to be solved, we develop a novel decomposition method that solves three kinds of smaller sub-models iteratively. The method is validated by comparing it with the integrated linear programming model using realistic demand data generated by a forecasting model. The method produces near-optimal solutions within three iterations. The decomposition method can also solve larger models much faster than the integrated model.
Elnaz Abdollahi; Risto Lahdelma. Decomposition method for optimizing long-term multi-area energy production with heat and power storages. Applied Energy 2019, 260, 114332 .
AMA StyleElnaz Abdollahi, Risto Lahdelma. Decomposition method for optimizing long-term multi-area energy production with heat and power storages. Applied Energy. 2019; 260 ():114332.
Chicago/Turabian StyleElnaz Abdollahi; Risto Lahdelma. 2019. "Decomposition method for optimizing long-term multi-area energy production with heat and power storages." Applied Energy 260, no. : 114332.
Low-temperature district heating (DH) with ring network and mass flow control was constructed and monitored in an existing apartment buildings in Kaarina, Finland. The extract air heat pump was connected in parallel to the area heating. Implementation of the new concept was successful. The study shows the right functioning of the system. The share of DH was 45% in the monitoring period and the rest of the heating was generated by the heat pump. The main result of the study is the practical construction of the new type of control and network planning strategy for the first time in practice after a series of research steps. Mainly, the practical study was in line with the theoretical results.
Maunu Kuosa; Sirpa Rahiala; Kirsi Tallinen; Tapio Mäkilä; Markku Lampinen; Risto Lahdelma; Lasse Pulkkinen. Mass flow controlled district heating with an extract air heat pump in apartment buildings: A practical concept study. Applied Thermal Engineering 2019, 157, 113745 .
AMA StyleMaunu Kuosa, Sirpa Rahiala, Kirsi Tallinen, Tapio Mäkilä, Markku Lampinen, Risto Lahdelma, Lasse Pulkkinen. Mass flow controlled district heating with an extract air heat pump in apartment buildings: A practical concept study. Applied Thermal Engineering. 2019; 157 ():113745.
Chicago/Turabian StyleMaunu Kuosa; Sirpa Rahiala; Kirsi Tallinen; Tapio Mäkilä; Markku Lampinen; Risto Lahdelma; Lasse Pulkkinen. 2019. "Mass flow controlled district heating with an extract air heat pump in apartment buildings: A practical concept study." Applied Thermal Engineering 157, no. : 113745.
The imperative to reduce emissions to counteract climate change has led to the use of renewables progressively in more areas. Looking at district heating, there is a growing interest in coupling current production systems and carbon-neutral technologies. This paper presents a methodology to support decision making about carbon-neutral technologies for district heating. The process is organized in two stages, the first one aims at optimizing the different carbon-neutral technologies according to an objective function and assess uncertainties and dependencies. In the second stage, the alternatives are evaluated using Stochastic Multicriteria Acceptability Analysis (SMAA), a simulation-based method specifically designed to consider imprecise information. The methodology was applied to a case-study in Torino, Italy, which simulates the city district heating network at a smaller scale, with the aim to explore strategies for replacing gas boiler with more sustainable technologies. According to preference information provided by decision makers, the most preferred alternative resulted in the introduction of a solar heat plant combined with an increase size of daily heat storage. Solar heat can benefit from incentives while reducing operational costs and emissions, maximizing the use of carbon-neutral heat thanks to the storage.
Giuseppe Pinto; Elnaz Abdollahi; Alfonso Capozzoli; Laura Savoldi; Risto Lahdelma. Optimization and Multicriteria Evaluation of Carbon-neutral Technologies for District Heating. Energies 2019, 12, 1653 .
AMA StyleGiuseppe Pinto, Elnaz Abdollahi, Alfonso Capozzoli, Laura Savoldi, Risto Lahdelma. Optimization and Multicriteria Evaluation of Carbon-neutral Technologies for District Heating. Energies. 2019; 12 (9):1653.
Chicago/Turabian StyleGiuseppe Pinto; Elnaz Abdollahi; Alfonso Capozzoli; Laura Savoldi; Risto Lahdelma. 2019. "Optimization and Multicriteria Evaluation of Carbon-neutral Technologies for District Heating." Energies 12, no. 9: 1653.
Renewable energy sources (RES) are playing an increasingly important role in energy markets around the world. It is necessary to evaluate the benefits from a higher level of RES integration with respect to a more active cross-border transmission system. In particular, this paper focuses on the sustainable energy transitions for Finland and Italy, since they have two extreme climate conditions in Europe and quite different profiles in terms of energy production and demand. We developed a comprehensive energy system model using EnergyPLAN with hourly resolution for a reference year for both countries. The models include electricity, heat and transportation sectors. According to the current base models, new scenarios reflecting an RES increase in total fuel consumption have been proposed. The future shares of renewables are based on each nation’s potential. The outcomes of the new scenarios support the future national plans, showing how decarburization in an energy system can occur in relation to the European Roadmap 2030 and 2050. In addition, possible power transmission between Italy and Finland were investigated according to the vision of an integrated European energy system with more efficient cross-border activities.
Haichao Wang; Giulia Di Pietro; Xiaozhou Wu; Risto Lahdelma; Vittorio Verda; Ilkka Haavisto. Renewable and Sustainable Energy Transitions for Countries with Different Climates and Renewable Energy Sources Potentials. Energies 2018, 11, 3523 .
AMA StyleHaichao Wang, Giulia Di Pietro, Xiaozhou Wu, Risto Lahdelma, Vittorio Verda, Ilkka Haavisto. Renewable and Sustainable Energy Transitions for Countries with Different Climates and Renewable Energy Sources Potentials. Energies. 2018; 11 (12):3523.
Chicago/Turabian StyleHaichao Wang; Giulia Di Pietro; Xiaozhou Wu; Risto Lahdelma; Vittorio Verda; Ilkka Haavisto. 2018. "Renewable and Sustainable Energy Transitions for Countries with Different Climates and Renewable Energy Sources Potentials." Energies 11, no. 12: 3523.
The complementary judgment matrix (CJM) method is an MCDA (multicriteria decision aiding) method based on pairwise comparisons. As in AHP, the decision-maker (DM) can specify his/her preferences using pairwise comparisons, both between different criteria and between different alternatives with respect to each criterion. The DM specifies his/her preferences by allocating two nonnegative comparison values so that their sum is 1. We measure and pinpoint possible inconsistency by inconsistency errors. We also compare the consistency of CJM and AHP trough simulation. Because preference judgments are always more or less imprecise or uncertain, we introduce a way to represent the uncertainty through stochastic distributions, and a computational method to treat the uncertainty. As in Stochastic Multicriteria Acceptability Analysis (SMAA), we consider different uncertainty levels: precise comparisons, imprecise comparisons with a stochastic distribution, and missing comparisons between criteria. We compute rank acceptability indices for the alternatives, describing the probability of an alternative to obtain a given rank considering the level of uncertainty and study the influence of the uncertainty on the SMAA-CJM results.
Haichao Wang; Risto Lahdelma; Pekka Salminen. Complementary Judgment Matrix Method with Imprecise Information for Multicriteria Decision-Making. Mathematical Problems in Engineering 2018, 2018, 1 -11.
AMA StyleHaichao Wang, Risto Lahdelma, Pekka Salminen. Complementary Judgment Matrix Method with Imprecise Information for Multicriteria Decision-Making. Mathematical Problems in Engineering. 2018; 2018 ():1-11.
Chicago/Turabian StyleHaichao Wang; Risto Lahdelma; Pekka Salminen. 2018. "Complementary Judgment Matrix Method with Imprecise Information for Multicriteria Decision-Making." Mathematical Problems in Engineering 2018, no. : 1-11.
Haichao Wang; Risto Lahdelma; Pekka Salminen. Stochastic multicriteria evaluation of district heating systems considering the uncertainties. Science and Technology for the Built Environment 2018, 24, 830 -838.
AMA StyleHaichao Wang, Risto Lahdelma, Pekka Salminen. Stochastic multicriteria evaluation of district heating systems considering the uncertainties. Science and Technology for the Built Environment. 2018; 24 (8):830-838.
Chicago/Turabian StyleHaichao Wang; Risto Lahdelma; Pekka Salminen. 2018. "Stochastic multicriteria evaluation of district heating systems considering the uncertainties." Science and Technology for the Built Environment 24, no. 8: 830-838.
Heidi Kirppu; Risto Lahdelma; Pekka Salminen. Multicriteria evaluation of carbon-neutral heat-only production technologies for district heating. Applied Thermal Engineering 2018, 130, 466 -476.
AMA StyleHeidi Kirppu, Risto Lahdelma, Pekka Salminen. Multicriteria evaluation of carbon-neutral heat-only production technologies for district heating. Applied Thermal Engineering. 2018; 130 ():466-476.
Chicago/Turabian StyleHeidi Kirppu; Risto Lahdelma; Pekka Salminen. 2018. "Multicriteria evaluation of carbon-neutral heat-only production technologies for district heating." Applied Thermal Engineering 130, no. : 466-476.
Haichao Wang; Lin Duanmu; Risto Lahdelma; Xiangli Li. A fuzzy-grey multicriteria decision making model for district heating system. Applied Thermal Engineering 2018, 128, 1051 -1061.
AMA StyleHaichao Wang, Lin Duanmu, Risto Lahdelma, Xiangli Li. A fuzzy-grey multicriteria decision making model for district heating system. Applied Thermal Engineering. 2018; 128 ():1051-1061.
Chicago/Turabian StyleHaichao Wang; Lin Duanmu; Risto Lahdelma; Xiangli Li. 2018. "A fuzzy-grey multicriteria decision making model for district heating system." Applied Thermal Engineering 128, no. : 1051-1061.
Nusrat Jung; Satu Paiho; Jari Shemeikka; Risto Lahdelma; Miimu Airaksinen. Energy performance analysis of an office building in three climate zones. Energy and Buildings 2018, 158, 1023 -1035.
AMA StyleNusrat Jung, Satu Paiho, Jari Shemeikka, Risto Lahdelma, Miimu Airaksinen. Energy performance analysis of an office building in three climate zones. Energy and Buildings. 2018; 158 ():1023-1035.
Chicago/Turabian StyleNusrat Jung; Satu Paiho; Jari Shemeikka; Risto Lahdelma; Miimu Airaksinen. 2018. "Energy performance analysis of an office building in three climate zones." Energy and Buildings 158, no. : 1023-1035.
Kristo Helin; Anssi Käki; Behnam Zakeri; Risto Lahdelma; Sanna Syri. Economic potential of industrial demand side management in pulp and paper industry. Energy 2017, 141, 1681 -1694.
AMA StyleKristo Helin, Anssi Käki, Behnam Zakeri, Risto Lahdelma, Sanna Syri. Economic potential of industrial demand side management in pulp and paper industry. Energy. 2017; 141 ():1681-1694.
Chicago/Turabian StyleKristo Helin; Anssi Käki; Behnam Zakeri; Risto Lahdelma; Sanna Syri. 2017. "Economic potential of industrial demand side management in pulp and paper industry." Energy 141, no. : 1681-1694.
Oskari Loikkanen; Risto Lahdelma; Pekka Salminen. Multicriteria evaluation of sustainable energy solutions for Colosseum. Sustainable Cities and Society 2017, 35, 289 -297.
AMA StyleOskari Loikkanen, Risto Lahdelma, Pekka Salminen. Multicriteria evaluation of sustainable energy solutions for Colosseum. Sustainable Cities and Society. 2017; 35 ():289-297.
Chicago/Turabian StyleOskari Loikkanen; Risto Lahdelma; Pekka Salminen. 2017. "Multicriteria evaluation of sustainable energy solutions for Colosseum." Sustainable Cities and Society 35, no. : 289-297.
Haichao Wang; Lin Duanmu; Risto Lahdelma; Xiangli Li. Developing a multicriteria decision support framework for CHP based combined district heating systems. Applied Energy 2017, 205, 345 -368.
AMA StyleHaichao Wang, Lin Duanmu, Risto Lahdelma, Xiangli Li. Developing a multicriteria decision support framework for CHP based combined district heating systems. Applied Energy. 2017; 205 ():345-368.
Chicago/Turabian StyleHaichao Wang; Lin Duanmu; Risto Lahdelma; Xiangli Li. 2017. "Developing a multicriteria decision support framework for CHP based combined district heating systems." Applied Energy 205, no. : 345-368.
A district heating (DH) system is one of the most important components of infrastructures in cold areas. Proper DH network design should balance the initial investment and the heat distribution cost of the DH network. Currently, this design is often based on a recommended value for specific pressure loss (R = ∆P/L) in the main lines. This will result in a feasible network design, but probably not be optimal in most cases. The paper develops a novel optimization model to facilitate the design by considering the initial investment in the pipes and the heat distribution costs. The model will generate all possible network scenarios consisting of different series of diameters for each pipe in the flow direction of the network. Then, the annuity on the initial investment, the heat distribution cost, and the total annual cost will be calculated for each network scenario, taking into account the uncertainties of the material prices and the yearly operating time levels. The model is applied to a sample DH network and the results indicate that the model works quite well, clearly identifying the optimal network design and demonstrating that the heat distribution cost is more important than the initial investment in DH network design.
Haichao Wang; Lin Duanmu; Xiangli Li; Risto Lahdelma. Optimizing the District Heating Primary Network from the Perspective of Economic-Specific Pressure Loss. Energies 2017, 10, 1095 .
AMA StyleHaichao Wang, Lin Duanmu, Xiangli Li, Risto Lahdelma. Optimizing the District Heating Primary Network from the Perspective of Economic-Specific Pressure Loss. Energies. 2017; 10 (8):1095.
Chicago/Turabian StyleHaichao Wang; Lin Duanmu; Xiangli Li; Risto Lahdelma. 2017. "Optimizing the District Heating Primary Network from the Perspective of Economic-Specific Pressure Loss." Energies 10, no. 8: 1095.
This paper deals with the transmission-constrained multi-site combined heat and power (CHP) problem and formulates it as a linear programming (LP) model with a special structure. CHP systems are treated as an extension of power-only systems. Each site can be treated as a regional energy system to supply both heat and power. Heat demand is satisfied by local production while power demand can be satisfied by local generation plus power exchange over the power network. The challenge of this problem is that power transmission needs to be coordinated with both power and heat production in each site. The transmission-constrained multi-site CHP system can be operated cost-efficiently according to hourly demand forecast for heat and power by coordinating production and transmission activities among different sites. An efficient network power Simplex algorithm is developed to this end. Numerical experiments with realistic test data show that the algorithm is 7–360 (with average 30) times faster than a commercial LPcode.Peer reviewe
Aiying Rong; Risto Lahdelma. An efficient model and algorithm for the transmission-constrained multi-site combined heat and power system. European Journal of Operational Research 2017, 258, 1106 -1117.
AMA StyleAiying Rong, Risto Lahdelma. An efficient model and algorithm for the transmission-constrained multi-site combined heat and power system. European Journal of Operational Research. 2017; 258 (3):1106-1117.
Chicago/Turabian StyleAiying Rong; Risto Lahdelma. 2017. "An efficient model and algorithm for the transmission-constrained multi-site combined heat and power system." European Journal of Operational Research 258, no. 3: 1106-1117.
Waltteri Salmi; Juha Vanttola; Mia Elg; Maunu Kuosa; Risto Lahdelma. Using waste heat of ship as energy source for an absorption refrigeration system. Applied Thermal Engineering 2017, 115, 501 -516.
AMA StyleWaltteri Salmi, Juha Vanttola, Mia Elg, Maunu Kuosa, Risto Lahdelma. Using waste heat of ship as energy source for an absorption refrigeration system. Applied Thermal Engineering. 2017; 115 ():501-516.
Chicago/Turabian StyleWaltteri Salmi; Juha Vanttola; Mia Elg; Maunu Kuosa; Risto Lahdelma. 2017. "Using waste heat of ship as energy source for an absorption refrigeration system." Applied Thermal Engineering 115, no. : 501-516.
Nusrat Jung; Munjur E.Moula; Tingting Fang; Mohamed Hamdy; Risto Lahdelma. Social acceptance of renewable energy technologies for buildings in the Helsinki Metropolitan Area of Finland. Renewable Energy 2016, 99, 813 -824.
AMA StyleNusrat Jung, Munjur E.Moula, Tingting Fang, Mohamed Hamdy, Risto Lahdelma. Social acceptance of renewable energy technologies for buildings in the Helsinki Metropolitan Area of Finland. Renewable Energy. 2016; 99 ():813-824.
Chicago/Turabian StyleNusrat Jung; Munjur E.Moula; Tingting Fang; Mohamed Hamdy; Risto Lahdelma. 2016. "Social acceptance of renewable energy technologies for buildings in the Helsinki Metropolitan Area of Finland." Renewable Energy 99, no. : 813-824.
Tingting Fang; Risto Lahdelma. Evaluation of a multiple linear regression model and SARIMA model in forecasting heat demand for district heating system. Applied Energy 2016, 179, 544 -552.
AMA StyleTingting Fang, Risto Lahdelma. Evaluation of a multiple linear regression model and SARIMA model in forecasting heat demand for district heating system. Applied Energy. 2016; 179 ():544-552.
Chicago/Turabian StyleTingting Fang; Risto Lahdelma. 2016. "Evaluation of a multiple linear regression model and SARIMA model in forecasting heat demand for district heating system." Applied Energy 179, no. : 544-552.