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In this paper we aim to make a comparison between three types of heat pumps: air-to-water, water-to-water, ground-to-water. We show that, from a construction point of view, the difference between the three types of heat pumps is the source from which the additional heat is extracted. We point out that the heat pump is the installation that transfers heat from a colder medium to a warmer medium. Most often, pumps extract heat from water, air or ground/geothermal sources and transfer it into the home via underfloor heating, radiators, etc. Any decision to install heat pump equipment must be carefully considered, taking into account all four elements (energy consumption, installation costs, existence of the chosen heat source and its accessibility) that influence the technical and economic efficiency and the proper functioning of the equipment. [ABSTRACT FROM AUTHOR]

The behavior of the processes taking place in furnaces determines the efficiency of fuel chemical energy utilization, the quality of the final products and the environmental safety of the production. Mathematical models of the processes of gas dynamics and heat transfer in the working space of heating equipment are quite complex, and do not allow the establishment of a direct analytical relationship between the quality indicator of the process (F) and the influencing parameters (xi). To simplify the procedure for obtaining the values of the function F depending on the change of parameters xi, a method of successive approximation is presented in the article. The main idea of the method is that the representation of the function around a point from the domain of the function can be extended to the entire domain for many problems of mechanics. The relative error in the definition of the function acquires its maximum value at the border of the area, and a reasonable narrowing of it allows control of the size of the error. Thus, the advantages of using the method are obvious; it is able to provide approximation of the function in a multiplicative form with a controlled error. The distribution of the method to the field of heat transfer problems is presented in this paper. The successful implementation of this method for solving problems of this kind shows that the solution of practical problems may be generalized for the entire domain of the function, despite the fact that the errors of such a representation increase to 5–7% when approaching its limit, which, however, may be considered acceptable for engineering calculations. [ABSTRACT FROM AUTHOR]

This paper presents the successful testing of a new high-efficiency indirect cooling technology in a cement milling application. Conventional cement cooling uses water flow that is open to the plant environment, leading to issues with efficiency, maintenance, emissions, and contamination. A new indirect cooling technology using cooling water enclosed within plates was tested at a Canadian cement plant, showing improved efficiency, and promises better maintenance and water usage. Test results are summarized and compared to the conventional cement cooling equipment. [ABSTRACT FROM AUTHOR]

Buildings are one of the biggest energy consumers in urban environments, so its efficient use represents a constant challenge. In public objects and households, a large part of the energy is used for heating and cooling. The orientation of the object, as well as the overall heat transfer coefficient (U-value) of transparent and non-transparent parts of the envelope, can have a significant impact on building energy needs. In this paper, analysis of the influence of different orientations, U-values of envelope elements, and size of windows on annual heating and cooling energy for an office building in city of Nis, Serbia, is presented. Model of the building was made in the Google SketchUp software, while the results of energy performance were obtained using EnergyPlus and jEplus, taking into account the parameters of thermal comfort and climatic data for the area of city of Nis. Obtained results showed that, for varied parameters, the maximum difference in annual heating energy is 15129.4 kWh, i. e per m2 27.75 kWh/m², while the maximum difference in annual cooling energy is 14356.1 kWh, i. e per m2 26.33 kWh/m². Considering that differences in energy consumption are significant, analysis of these parameters in the early stage of design process can affect on increase of building energy efficiency. [ABSTRACT FROM AUTHOR]

Thermal management is a key design aspect of power converters since it determines their reliability as well as their final performance and power density. Cooling technologies have been a research area in electronics since the 1940s and, in the last 15 years, the number of articles related to this field has grown significantly. At present, thermal management is essential in new disciplines and it is a critical enabling technology in the development of power electronic systems. This paper aims at presenting a review of the state-of-the-art technology and provides future design guidelines for high efficiency power electronic converters. The main design trends are focused on the need to develop cooling systems able to manage high local density heat fluxes due to two converging trends: higher power dissipation and smaller module size. Considering the latest advances in thermal management, as well as the huge improvement in power electronics in the last decades, a review and classification of the main thermal management techniques is presented. Besides, they are compared considering important parameters such as peak power dissipation, efficiency, cost/complexity, power density or technical maturity, and a design example for an ultrahigh efficiency converter is presented. [ABSTRACT FROM PUBLISHER]

Cold weather is an important matter for electric and hybrid-electric vehicles (EV/HEVs), because the electro-chemical process is slowed at low temperatures, hence inducing a loss of power and energy. To prevent it from happening, battery packs are heated via a battery thermal management system (BTMS). However, in some cases, HEVs/EVs are not connected to the grid, so the BTMS uses energy from the battery pack, thus impacting total autonomy. Strategies exist, but must be optimized. Therefore, this paper proposes the design of a HEV strategy that is parked outside and unplugged from the electrical grid. Its objective is to find a compromise between the cost in energy contained in the battery and the aging of the cells. The optimization is based on dynamic programming and utilizes an electro-thermal battery model including aging. Simulation results are then compared with other strategies, underlining that parking outside at work or overnight without plugging in are issues with the actual strategies of common EVs/HEVs, mainly because aging as a result of cold temperatures is not considered. [ABSTRACT FROM PUBLISHER]

The purpose of the research was to examine the savings potential and verify how to reduce the energy consumption in new hospitals by about 50%. Our results are also very relevant in other buildings complex with surplus heating, cooling and thermal storage. Conversion and utilization of surplus heat sources represent well known technologies and are under constant development. In large building complexes there is a potential for coordinated production, storage, and distribution of energy. Heat pump, chiller and thermal storage technologies enable re-use of surplus heat/cool energy throughout the year. Energy supply and demand are typically modelled with separate tools and timescales. Through our study new methods are developed for operation of interacting simulating models. These methods provide tools to step into optimization of combinations of integrated energy systems. The main issues focus on hydraulic water flow and storage systems as a basis. The layout is important not only with regards to utilize the energy quality, i.e. the temperature. In addition, control strategies are shown to have a highly relevant impact on the possible savings. Some details of new hydraulic layout and control design will be described and discussed in the paper. Both in combination with heating, cooling and storage system. Our research indicates that it is possible to save between 20-50% of the energy consumption with optimizing the technical installations in Oslo area. Another benefit of integrated thermal modelling is to reduce the risk of permafrost in ground source heat pump installations. This risk is relevant for large buildings in northern Norway, at annual mean temperatures are below 0̊C. This paper shows how integrated simulation and design can be used to avoid permafrost. [ABSTRACT FROM AUTHOR]

As one of the energy-efficient heating technologies, earth air heat exchangers (EAHE) use renewable energy (i.e. geo-thermal energy) to first heat outdoor air, and then supply it to indoors for space heating in winter. The aim of this paper is to study the thermal performance of EAHE in winter in hot summer and cold winter areas. An experimental setup of EAHE was established in Changsha, China. Different variables, including soil temperature, supply air temperature and outdoor air temperature were measured for one week. The thermal performance was evaluated based on the data analysis. Results show that the supply air temperature reached the soil temperature around the pipe at the same length of 20m for different inlet air temperature. The COP and Q decreased along with the increase of inlet air temperature but increased along with the pipe length. Moreover, the thermal saturation of soil occurred in the fifth day of the week, and thermal interference between pipes can be ignored under the 1m distance between pipes. Our future work includes developing a numerical model to analyze and optimize the thermal performance of EAHE, thereby providing a reference for its design and application in hot summer and cold winter areas in China. [ABSTRACT FROM AUTHOR]

• A new enclosed melting system was built for deicing the bottom of a train. • A new method was used for simulating gravity shedding melting in complex models. • The effect of supply air properties on system performance was studied. In winter, a large amount of icing and snowing occurs in outdoor equipment and systems, which adversely affects their lifespan. The melting process is divided into two parts: convection melting and gravity shedding melting. This paper is based on an experiment with a real high-speed train unit, and it establishes a three-dimensional computational fluid dynamics model of the bogie area to validate the mathematical model of the winter ice melting experiment. A numerical simulation was used to calculate the airflow in the baffle-enclosed space and to predict the effects of interactions between air and the ice body on heat transfer and phase change. The influence of air velocity and temperature on the heat transfer was analyzed. The computational simulation effectively quantifies the amount of heat transfer and energy consumption under different conditions. This paper also presents a research method for the simulation of gravity shedding in complex models. These models provide information for the construction of similar ice melting models. This paper has suggested that for thin ice bodies, convection melting was the dominant strategy. For thick ice bodies, however, gravity shedding melting became dominant. The study also confirmed that enclosed hot-air ice-melting systems gave a better energy performance than unenclosed systems. [ABSTRACT FROM AUTHOR]

• A new methodology to investigate the impact of thermal mass is defined. • The use of unrepresentative boundary conditions could lead to inaccurate conclusions. • High thermal mass helps to decrease and regulate the internal temperature. • High thermal mass could increase energy use in the summer and winter seasons. • Isolating thermal mass through internal insulation results in better energy performance than external insulation. Contradictory conclusions have been reported on whether thermal mass reduces or increases energy demand in hot and cold climates. A novel approach to measuring the impact of thermal mass on the building's energy consumption is presented. The method aims to better represent reality and applies two different control conditions simultaneously in a numerical model: the first condition, which has been used in past studies, adjusts the internal boundary condition based on the time duration of heating/cooling activation (simulating an occupancy pattern) and the second, which has not been used in past studies, adjusts the internal boundary condition based on both the time duration and the internal temperature (simulating an occupancy pattern and the thermostatic control system). When investigating the impact of thermal mass on the internal temperature in a scenario where no heat is transferred into the building, the high thermal mass outperforms the low thermal mass, showing a time-shifting effect, long time lag, and small decrement factor. However, when modelled using the method presented in this paper, high thermal mass results in greater energy consumption during summer and winter periods in Saudi Arabia. During transition seasons where temperature swings occur on either side of the indoor set-point temperatures, thermal mass reduces thermal transmission. The impact of thermal mass is also investigated for several climatic conditions in Saudi Arabia. Simulation results show that an internally exposed thermal massive wall section results in greater energy consumption when compared to a similar building with isolated thermal mass (i.e. insulated internally). This is due to the fact that even though the internal temperature inside the building is being cooled/warmed up to the set-point, the thermal mass continues to transfer heat that is absorbed by the building's fabric from/to the interior, placing a greater demand on the cooling/heating system. Over the course of a year, however, the impact of thermal mass is negligible when compared to other factors, such as the insulative properties of the building's fabric. [ABSTRACT FROM AUTHOR]

The trend toward increasing energy efficiency and variable renewable energy (VRE) production has implications for combined heat and power (CHP) plants, which operate in both the price-driven power market and the district heating (DH) sector. Since CHP will be important in VRE integration, we develop a complementarity model to analyze CHP producers’ roles in integrated markets. We use a Nordic case study to gain insights into, first, the effect of the link between CHP and DH on market power and, second, market power's impact on operations in the DH sector. The results indicate that, first, the link of CHP to DH supply can increase market power and, second, market power can induce shifts in DH production from heat only to CHP. [ABSTRACT FROM AUTHOR]

The main objective of this study is to assess the potential for energy savings in the cooling water circuit of a vessel through the use of variable speed drives (VSDs). A small-scale cooling system was set up in the laboratory and relevant tests were carried out by simulating field conditions. Moreover, the payback period from VSDs installation on an existing 8000 TEU container ship based on the operational scenario of a representative journey was calculated. The result of the analysis revealed significant savings with a payback period of only a few months for VSD-controlled sea water pumps of a container vessel. [ABSTRACT FROM AUTHOR]

To address the large temperature difference in the air heater (AH) inlet of a traditional exhaust heat utilization system and energy grade mismatch problems during the heat and mass transfer processes, this study proposed a new multi-level waste heat cascade utilization system. Based on a principle of "temperature-to-port and cascade utilization", this system uses the boiler side high-temperature flue gas and low-temperature air, and the turbine side high-temperature feed water and low-temperature condensate water, to conduct cross heat exchange according to the energy grade matching principle. Combined with a typical 1000 MW coal-fired unit, the heat transfer characteristics and energy-saving benefits of the new system were analyzed. The results showed that the new system has excellent performance: the heat rate decreased by 91 kJ/kWh, coal consumption decreased by 3.3 g/kWh, and power generation efficiency increased to 49.39%. [ABSTRACT FROM AUTHOR]

High mountains and cold climate in the north-west of Iran are critical factors for the design of optimized District Heating (DH) systems and energy-efficient buildings. It is essential to consider the Life Cycle Cost (LCC) that includes all costs, such as initial investment and operating costs, for designing an optimum DH system. Moreover, considering climate change for accurately predicting the required heating load is also necessary. In this research, a general optimization is carried out for the first time with the aim of a new design concept of a DH system according to a LCC, while considering all-involved parameters. This optimized design is based on various parameters such as ceiling and wall insulation thicknesses, depth of buried water and heating supply pipes, pipe insulation thickness, and boiler outlet temperature. In order to consider the future weather projection, the mentioned parameters are compared with and without climate change effects in a thirty-year period. The location selection was based on the potential of the region for such a system together with the harsh condition of the area to transport the common fossil fuel to the residential buildings. The obtained results show that insulation of walls is more thermally efficient than a roof with the same area in the selected case. In this case, polyurethane is the best material, which can cause a reduction of 59% in the heating load and, consequently, 2332 tons of CO2 emission annually. The most and the least investment payback periods are associated with the polyurethane and the glass wool insulation materials with the amounts of seven and one years. For the general optimization of the DH system, the Particle Swarm Optimization (PSO) method with a constriction coefficient was chosen. The results showed that the optimal thickness of the polyurethane layer for the thermal insulation of the building exterior walls is about 14 cm and the optimal outlet temperature of the boiler is about 95 °C. It can be also concluded that the optimal depth for the buried pipes is between 1.5 to 3 m underground. In addition, for the pipe with elastomeric insulation layer, the thickness of 2 cm is the optimal choice. [ABSTRACT FROM AUTHOR]