scholarly journals INVESTIGATION OF THE ENERGY RECOVERY POTENTIALS IN VENTILATION SYSTEMS IN DIFFERENT CLIMATES

2018 ◽  
Vol 16 (2) ◽  
pp. 203 ◽  
Author(s):  
Miklos Kassai ◽  
Laszlo Poleczky ◽  
Laith Al-Hyari ◽  
Laszlo Kajtar ◽  
Jozsef Nyers
Keyword(s):  
Energy Recovery ◽  
Heat Recovery ◽  
Climatic Conditions ◽  
Operating Conditions ◽  
Weather Data ◽  
High Definition ◽  
Engineering Practices ◽  
Available Information ◽  
Different Climates ◽  
Ventilation Systems

The aim of this research study was to investigate the energy recovery potentials in ventilation systems under different climatic conditions. The well-known heating degree day from the literature was updated using the weather data of cities with different climates from the past 40 years. As the novelty of this research with the developed procedure drawn up in this study, the energetic possibilities of heat recovery under various climate and operating conditions may be examined in more detail and more realistically than with the methods and available information of current engineering practices. To achieve this long-term and high definition the weather data of several cities are processed in order to evaluate the possibilities of heat recovery on a daily and annual basis.

scholarly journals Heat Recovery Ventilation Systems and their Physical Quantification

2021 ◽  
Vol 1203 (2) ◽  
pp. 022045
Author(s):  
Boris Bielek ◽  
Daniel Szabó ◽  
Josip Klem ◽  
Roman Grolmus
Keyword(s):  
Energy Efficiency ◽  
Heat Recovery ◽  
Ventilation System ◽  
Co2 Concentration ◽  
High Energy ◽  
Operating Conditions ◽  
Indoor Climate ◽  
Measurement Results ◽  
Ventilation Systems

Abstract The essence of ventilation is the exchange of air in the room for fresh outside air. At the same time ventilation is a factor that can significantly affect the energy efficiency of a building. Hygienic requirements for ventilation of interiors of buildings in the context of increasing the energy efficiency of buildings lead to the transformation of unregulated ventilation by infiltration to regulated ventilation systems with heat recovery. The regulated ventilation system makes it possible to optimize the ventilation intensity on the basis of a stimulus from the room user or automatically on the basis of sensors monitoring the quality of the indoor climate (temperature and relative humidity, CO2 concentration in the air, etc.). In addition, if we use a ventilation system with heat recovery from the exhaust air to preheat the fresh supply air to the room, we can achieve high energy efficiency of the building by meeting the hygienic criteria of the indoor climate. The article describes heat recovery ventilation systems and their basic conceptual solutions applied in the modern architecture. The heat exchange between the hot exhaust air and the cold supply air in the winter takes place in heat recovery ventilation units in the heat exchanger. The efficiency of heat recovery defines how much heat we can transfer from the exhaust air to the fresh air in the heat recovery exchanger. The article analyses individual factors influencing the efficiency of heat recovery. Due to the fact that the manufacturers of heat recovery ventilation units declare in their brochures or websites the values of the maximum efficiencies of their products, we were interested in their real efficiencies under normal operating conditions. Therefore, we subjected to experimental research in a large climate chamber a product from the German manufacturer Lunos, namely a specific type of decentralized heat recovery unit Lunos Nexxt E. The article describes the methodology of laboratory experiment, used experimental basis, brings and analyses measurement results and calculates real efficiency of the subject heat recovery in accordance with STN EN 13 141. In the end it compares measured values with the values from the manufacturer.

scholarly journals EXERGY-BASED CONTROL STRATEGY IN A DWELLING VENTILATION SYSTEM WITH HEAT RECOVERY

2020 ◽  
Vol 10 (2) ◽  
pp. 44-47
Author(s):  
Volodymyr Voloshchuk ◽  
Mariya Polishchuk
Keyword(s):  
Heat Recovery ◽  
Operation Mode ◽  
Ventilation System ◽  
Primary Energy ◽  
Climatic Conditions ◽  
Operating Conditions ◽  
Spent Fuel ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Operational Modes

The paper presents energy and exergy analysis of a typical dwelling ventilation system with heat recovery for Ukrainian climatic conditions using a quasi-steady state approach over 24-hour time-steps. Evaluation of such systems on the base of the first law of thermodynamics demonstrates that heat recovery is beneficial for the whole variety of operational modes. Such methodology identifies as a thermodynamic inefficiency only energy losses to the surroundings with the exhaust air. The exergy-based analysis can detect additional inefficiencies due to irreversibilities within the components of the system. As a result the exergetic investigations show that for the ventilation systems there are operating conditions for which heat recovery increases exergy of fuel expended to provide the ventilation air compared to cases without bringing any recovery of heat and additional power consumption to drive the air flow by the fans. For the specified system, in case of switching ventilation unit to the operation mode of lower values of spent fuel exergy it is possible to provide annual saving of the primary energy sources from 5 to 15%.

Energy Recovery by the Incineration of Solid Waste Development, Present Status, and Experiences in Germany

1976 ◽  
Vol 190 (1) ◽  
pp. 601-610
Author(s):  
K. H. Thömen
Keyword(s):  
Solid Waste ◽  
Heat Production ◽  
Present Status ◽  
Energy Recovery ◽  
Heat Recovery ◽  
Operating Conditions ◽  
Boiler Tubes ◽  
Planning And Construction

Starting with a review of the development of incinerator plants from simple destruction units to installations for heat recovery, the author surveys different aspects of a complex theme. Using the concept of ‘heat production’, the composition of the refuse and the operating conditions which are important in the planning and construction of an incinerator are considered. The paper then discusses the choice of furnace equipment and the conditions to be imposed on it, using as an example the ‘Düsseldorf roller grate system’. The configuration of the furnaces is also dealt with in the light of experience in the construction of the boilers. Finally, under the heading ‘Operating Experiences’, facts are given about the reliability of incinerators, with special emphasis upon the problem of corrosion of the boiler-tubes.

scholarly journals Component-Oriented Modeling of a Micro-Scale Organic Rankine Cycle System for Waste Heat Recovery Applications

2021 ◽  
Vol 11 (5) ◽  
pp. 1984
Author(s):  
Ramin Moradi ◽  
Emanuele Habib ◽  
Enrico Bocci ◽  
Luca Cioccolanti
Keyword(s):  
Electric Power ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Pump Efficiency ◽  
Micro Scale

Organic Rankine cycle (ORC) systems are some of the most suitable technologies to produce electricity from low-temperature waste heat. In this study, a non-regenerative, micro-scale ORC system was tested in off-design conditions using R134a as the working fluid. The experimental data were then used to tune the semi-empirical models of the main components of the system. Eventually, the models were used in a component-oriented system solver to map the system electric performance at varying operating conditions. The analysis highlighted the non-negligible impact of the plunger pump on the system performance Indeed, the experimental results showed that the low pump efficiency in the investigated operating range can lead to negative net electric power in some working conditions. For most data points, the expander and the pump isentropic efficiencies are found in the approximate ranges of 35% to 55% and 17% to 34%, respectively. Furthermore, the maximum net electric power was about 200 W with a net electric efficiency of about 1.2%, thus also stressing the importance of a proper selection of the pump for waste heat recovery applications.

Impact of climatic conditions on the parameters of failure flow of military vehicles

2021 ◽  
pp. 095440702110202
Author(s):  
Nikolaj Dobrzinskij ◽  
Algimantas Fedaravicius ◽  
Kestutis Pilkauskas ◽  
Egidijus Slizys
Keyword(s):  
Climatic Factors ◽  
Armed Forces ◽  
Climatic Conditions ◽  
Operating Conditions ◽  
Technical Equipment ◽  
Factors Affecting ◽  
Military Vehicles ◽  
Equipment Reliability ◽  
Number Of Factors ◽  
The Impact

Relevance of the article is based on participation of armed forces in various operations and exercises, where reliability of machinery is one of the most important factors. Transportation of soldiers as well as completion of variety of tasks is ensured by properly functioning technical equipment. Reliability of military vehicles – armoured SISU E13TP Finnish built and HMMWV M1025 USA built were selected as the object of the article. Impact of climatic conditions on reliability of the vehicles exploited in southwestern part of the Atlantic continental forest area is researched by a case study of the vehicles exploitation under conditions of the climate of Lithuania. Reliability of military vehicles depends on a number of factors such as properties of the vehicles and external conditions of their operation. Their systems and mechanisms are influenced by a number of factors that cause different failures. Climatic conditions represent one of the factors of operating load which is directly dependent on the climate zone. Therefore, assessment of the reliability is started with the analysis of climatic factors affecting operating conditions of the vehicles. Relationship between the impact of climatic factors and failure flow of the vehicles is presented and discussed.

Improving the Volumetric Efficiency of the Axial Piston Pump

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
Shu Wang
Keyword(s):  
Operating Conditions ◽  
Volumetric Efficiency ◽  
Valve Plate ◽  
Piston Pump ◽  
Efficient Design ◽  
Axial Piston Pumps ◽  
Definition Of ◽  
Engineering Practices ◽  
First Time ◽  
Axial Piston

The volumetric efficiency is one of the most important aspects of system performance in the design of axial piston pumps. From the standpoint of engineering practices, the geometric complexities of the valve plate (VP) and its multiple interactions with pump dynamics pose difficult obstacles for optimization of the design. This research uses the significant concept of pressure carryover to develop the mathematical relationship between the geometry of the valve plate and the volumetric efficiency of the piston pump. For the first time, the resulting expression presents the theoretical considerations of the fluid operating conditions, the efficiency of axial piston pumps, and the valve plate designs. New terminology, such as discrepancy of pressure carryover (DPC) and carryover cross-porting (CoCp), is introduced to explain the fundamental principles. The important results derived from this study can provide clear recommendations for the definition of the geometries required to achieve an efficient design, especially for the valve plate timings. The theoretical results are validated by simulations and experiments conducted by testing multiple valve plates under various operating conditions.

Field survey on frost damage to roof tiles under climatic conditions

2016 ◽  
Vol 34 (2) ◽  
pp. 135-149 ◽  
Author(s):  
Chiemi Iba ◽  
Ayumi Ueda ◽  
Shuichi Hokoi
Keyword(s):  
Field Survey ◽  
Winter Season ◽  
Frost Damage ◽  
Climatic Conditions ◽  
Weather Data ◽  
Measured Temperature ◽  
Content Type ◽  
Roof Tile ◽  
Deterioration Process ◽  
The Impact

Purpose – Frost damage is well-known as the main cause of roof tile deterioration. The purpose of this paper is to develop an analytical model for predicting the deterioration process under certain climatic conditions. This paper describes the results of a field survey conducted to acquire fundamental information useful to this aim. Design/methodology/approach – A field survey of roof tile damage by freezing was conducted in an old temple precinct in Kyoto, Japan. Using detailed observations and photographic recordings, the damage progress was clarified. To examine the impact of climatic conditions upon the damage characteristics, weather data and roof tile temperatures were measured and logged in the winter season. Findings – The deterioration process was observed under the climatic conditions associated with the measured temperature of the roof tiles. In particular, it was revealed that the orientation has a significant influence on increasing or decreasing the risk of frost damage. For certain distinctive forms of damage, the deterioration mechanisms were estimated from the viewpoint of the moisture flow and temperature distribution in the tile. Originality/value – This study contributes to the elucidation of the mechanism behind frost damage to roof tiles. The findings will guide the construction of a numerical model for frost damage prediction.

scholarly journals Analysis of Capacitance to Ground Formulas for Different High-Voltage Electrodes

Energies ◽  
2018 ◽  
Vol 11 (5) ◽  
pp. 1090 ◽  
Author(s):  
Jordi-Roger Riba ◽  
Francesca Capelli
Keyword(s):  
High Voltage ◽  
Fem Simulation ◽  
Operating Conditions ◽  
Power Supplies ◽  
Measuring Instruments ◽  
Stray Capacitance ◽  
Analytical Formulas ◽  
Circular Rings ◽  
Available Information ◽  
Limited Scope

Stray capacitance can seriously affect the behavior of high-voltage devices, including voltage dividers, insulator strings, modular power supplies, or measuring instruments, among others. Therefore its effects must be considered when designing high-voltage projects and tests. Due to the difficulty in measuring the effects of stray capacitance, there is a lack of available experimental data. Therefore, for engineers and researchers there is a need to revise and update the available information, as well as to have useful and reliable data to estimate the stray capacitance in the initial designs. Although there are some analytical formulas to calculate the capacitance of some simple geometries, they have a limited scope. However, since such formulas can deal with different geometries and operating conditions, it is necessary to assess their consistency and applicability. This work calculates the stray capacitance to ground for geometries commonly found in high-voltage laboratories and facilities, including wires or rods of different lengths, spheres and circular rings, the latter ones being commonly applied as corona protections. This is carried out by comparing the results provided by the available analytical formulas with those obtained from finite element method (FEM) simulation, since field simulation methods allow solving such problem. The results of this work prove the suitability and flexibility of the FEM approach, because FEM models can deal with wider range of electrodes, configurations and operating conditions.

Waste Heat Recovery in a Cruise Vessel in the Baltic Sea by Using an Organic Rankine Cycle: A Case Study

2015 ◽  
Author(s):  
Fredrik Ahlgren ◽  
Maria E. Mondejar ◽  
Magnus Genrup ◽  
Marcus Thern
Keyword(s):  
Power Output ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Maritime Transportation ◽  
Working Fluid ◽  
Net Power Output

Maritime transportation is a significant contributor to SOx, NOx and particle matter emissions, even though it has a quite low CO2 impact. New regulations are being enforced in special areas that limit the amount of emissions from the ships. This fact, together with the high fuel prices, is driving the marine industry towards the improvement of the energy efficiency of current ship engines and the reduction of their energy demand. Although more sophisticated and complex engine designs can improve significantly the efficiency of the energy systems in ships, waste heat recovery arises as the most influent technique for the reduction of the energy consumption. In this sense, it is estimated that around 50% of the total energy from the fuel consumed in a ship is wasted and rejected in fluid and exhaust gas streams. The primary heat sources for waste heat recovery are the engine exhaust and the engine coolant. In this work, we present a study on the integration of an organic Rankine cycle (ORC) in an existing ship, for the recovery of the main and auxiliary engines exhaust heat. Experimental data from the operating conditions of the engines on the M/S Birka Stockholm cruise ship were logged during a port-to-port cruise from Stockholm to Mariehamn over a period of time close to one month. The ship has four main engines Wärtsilä 5850 kW for propulsion, and four auxiliary engines 2760 kW used for electrical consumers. A number of six load conditions were identified depending on the vessel speed. The speed range from 12–14 knots was considered as the design condition, as it was present during more than 34% of the time. In this study, the average values of the engines exhaust temperatures and mass flow rates, for each load case, were used as inputs for a model of an ORC. The main parameters of the ORC, including working fluid and turbine configuration, were optimized based on the criteria of maximum net power output and compactness of the installation components. Results from the study showed that an ORC with internal regeneration using benzene would yield the greatest average net power output over the operating time. For this situation, the power production of the ORC would represent about 22% of the total electricity consumption on board. These data confirmed the ORC as a feasible and promising technology for the reduction of fuel consumption and CO2 emissions of existing ships.

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