Continuous Operating Elastocaloric Heating and Cooling Device: Air Flow Investigation and Experimental Parameter Study

2019 ◽  
Author(s):  
Susanne-Marie Kirsch ◽  
Felix Welsch ◽  
Lukas Ehl ◽  
Nicolas Michaelis ◽  
Paul Motzki ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Air Flow ◽  
Experimental Parameter ◽  
Rotation Frequency ◽  
Coefficient Of Performance ◽  
Large Temperature ◽  
Parameter Study ◽  
Or Efficiency ◽  
Heating And Cooling

Abstract Elastocaloric cooling uses solid-state NiTi-based shape memory alloy (SMA) as a non-volatile cooling medium and enables a novel environment-friendly cooling technology without global warming potential. Due to the high specific latent heats activated by mechanical loading/unloading, large temperature changes can be generated in the material. Accompanied by a small required work input, a high coefficient of performance is achievable. Recently, a fully-functional and illustrative continuous operating elastocaloric fluid cooling system based on SMA is developed and realized, using a novel mechanical concept for individual loading and unloading of multiple SMA wire bundles. The fluid-based heat transfer system is designed for efficient heat exchange between the stationary heat source/sink and the SMA elements, operates without any additional heat transfer medium. Rotation frequency and fluid flow-rate are adjustable during operation, which allows adapting the operation point to power- or efficiency-optimized demands. The versatile placement of the in- and outlets allows different duct lengths and counter-flow or parallel-flow experiments. To investigate the air flow parameters at the in- and outlets, as well as the crossflow between the hot and cold side, a measurement system is developed and integrated. In this contribution, the first measurement results of the output temperatures for inlet air flow variation in combination with different rotation frequencies are presented.

scholarly journals Numerical Evaluation of a HVAC System Based on a High-Performance Heat Transfer Fluid

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3298
Author(s):  
Gianpiero Colangelo ◽  
Brenda Raho ◽  
Marco Milanese ◽  
Arturo de Risi
Keyword(s):  
Heat Transfer ◽  
High Performance ◽  
Cooling System ◽  
Electrical Energy ◽  
Simulation Software ◽  
Heat Transfer Fluid ◽  
Hvac System ◽  
Dynamic Simulations ◽  
Heating And Cooling ◽  
The University

Nanofluids have great potential to improve the heat transfer properties of liquids, as demonstrated by recent studies. This paper presents a novel idea of utilizing nanofluid. It analyzes the performance of a HVAC (Heating Ventilation Air Conditioning) system using a high-performance heat transfer fluid (water-glycol nanofluid with nanoparticles of Al2O3), in the university campus of Lecce, Italy. The work describes the dynamic model of the building and its heating and cooling system, realized through the simulation software TRNSYS 17. The use of heat transfer fluid inseminated by nanoparticles in a real HVAC system is an innovative application that is difficult to find in the scientific literature so far. This work focuses on comparing the efficiency of the system working with a traditional water-glycol mixture with the same system that uses Al2O3-nanofluid. The results obtained by means of the dynamic simulations have confirmed what theoretically assumed, indicating the working conditions of the HVAC system that lead to lower operating costs and higher COP and EER, guaranteeing the optimal conditions of thermo-hygrometric comfort inside the building. Finally, the results showed that the use of a nanofluid based on water-glycol mixture and alumina increases the efficiency about 10% and at the same time reduces the electrical energy consumption of the HVAC system.

Research of Combined Heating and Cooling by Solar Ground-Source Heat Pump and PCM Thermal Storage

Solar Energy ◽  
2005 ◽  
Author(s):  
Li-Xia Wu ◽  
Mao-Yu Zheng
Keyword(s):  
Heat Exchanger ◽  
Solar Energy ◽  
Cooling System ◽  
Storage System ◽  
Thermal Storage ◽  
Cold Climate ◽  
Coefficient Of Performance ◽  
Tube Heat Exchanger ◽  
Heating And Cooling ◽  
Ground Source

In severely cold climate, significant amount of energy is used to heat buildings. Both the theoretical computation and experiments show that it is difficult and uneconomical to use solar energy collected merely in winter. A new method has been developed to store solar energy during summer, fall, and spring for winter heating. This paper presents in details the combined heating and cooling system by solar ground-source heat pump (GSHP) and short-term phase change material (PCM) thermal storage. The hybrid system and season-shift mode can make the sustainable use of solar energy possible. As for the above system, the solar energy collected is stored into soil through the U-tube heat exchanger. In winter, the thermal energy is taken out for heating using the GSHP. At the end of the heat supply season, the underground soil temperature may drop below 0°C. Then some heat exchangers begin to store the heat into soil while others stop. In summer, the U-tube heat exchanger is used to produce low temperature water without compressor to cool the room. The project was supported by the Energy Conservation Laboratory at Harbin Institute of Technology (HIT). The whole systems, which have run for over two years, consist of a flat plate solar hot water system installed on the roof, a soil thermal storage system, a GSHP system, a PCM thermal storage system and heating-cooling system. The measured results show an average heating coefficient of performance (COP) of 3.2 in winter and the cooling coefficient of performance (COP) of 18.0 in summer. The PCM thermal storage system has been investigated by numerical simulation and experiments in the cold climate. In most time of winter, the PCM thermal storage system was used to supply heat, while solar GSHP was also used during continuous cloudy days and severely cold days. The result shows that above method is feasible. The most advantage of this system is that it does not need the usual energy equipment. The numerical analysis has been used to investigate the thermal energy balance of the underground soil. The variation of the soil temperature field around the U-tube heat exchanger has also been studied, not only for the single exchanger but also for multiple exchangers. The underground soil makes the yearly thermal balance possible because the solar energy supplies the heat that is extracted from the soil for heating in winter. Then this system can operate for a long period.

Simulation Study of the Heat and Mass Recovery on the Performance of Adsorption Cooling Systems

2014 ◽  
Author(s):  
K. C. Chan ◽  
C. Y. Tso ◽  
Christopher Y. H. Chao
Keyword(s):  
System Performance ◽  
Heat Recovery ◽  
Cooling System ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Cooling Systems ◽  
Heating And Cooling ◽  
Adsorption Cooling System ◽  
Heat And Mass Recovery ◽  
Mass Recovery

In this study, simulation was conducted to investigate the effect of mass recovery, heat recovery, pre-heating and pre-cooling time on the system performance of a double-bed adsorption cooling system. Pressures of different system components were considered in the simulation. The adsorbent-adsorbate pair used was silica-gel and water. The heating and cooling temperatures were selected to be 85°C and 27°C respectively. Both the adsorption and desorption phase times were set at 15 minutes. The coefficient of performance (COP) and specific cooling power (SCP) were used to quantify the performance of the system. From the simulation, the basic cycle provided COP and SCP of 0.20 and 40.9W/kg respectively. By conducting heat recovery for 120 seconds, the system COP was largely increased by 99% to 0.40 compared to the basic cycle. The SCP was also increased to 42.3W/kg. Mass recovery, however, did not have too much effect on the system performance. The COP and SCP only increased by 4.5% and 3.9% respectively when conducting mass recovery for 4.7 seconds. For conducting heat and mass recovery, the COP and SCP were increased to 0.36 and 44.68W/kg, respectively. Pre-heating and pre-cooling can also be beneficial in improving both COP and SCP. The COP and SCP were increased by 14.5% and 10.1% respectively, to 0.23 and 45.0W/kg by conducting pre-heating and pre-cooling for 50.3 seconds. The combinations of these processes were also studied. It is suggested heat and mass recovery then pre-heating and pre-cooling should be conducted to improve COP and SCP. The improvements showed 31.2% for COP, increasing to 0.27, and 11.9% for SCP, increasing to 45.7W/kg.

Cooling and heating rate limits of a reversed reciprocating ericsson cycle at steady state

2000 ◽  
Vol 214 (1) ◽  
pp. 75-85 ◽  
Author(s):  
D A Blank ◽  
C Wu
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Heat Pump ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Design Parameters ◽  
Optimized Design ◽  
Cooling Mode ◽  
Working Fluids ◽  
Heating And Cooling

The optimal cooling and heating rates for the reversed reciprocating Ericsson cycle with ideal regeneration are determined for heat pump operations. These limiting rates are based on the upper and lower thermal reservoir temperature bounds and are obtained using time and entropy minimization procedures from irreversible thermodynamics. Use is made of time symmetry (a second law constraint) to minimize cycle time. This optimally allocates the thermal capacitances of the cycle and minimizes internal cycle entropy generation. Although primarily a theoretical work, a very practical and extensive parametric study using several environmentally friendly working fluids (neon, nitrogen and helium) is included. This study evaluates the relative contributions of various system parameters to rate-optimized design. The coefficient of performance (COP), and thus the quantity of cooling or heating for a given energy input, is the traditional focus; instead this work aims at the rate of cooling or heating in heat pumps under steady state conditions and using ideal gases as their working substances. The results obtained provide additional criteria for use in the study, design and performance evaluation of employing Ericsson cycles in refrigeration, air conditioning and heat pump applications. They give direct insight into what is required in designing a reversed Ericsson heat pump to achieve maximum heating and cooling rates. The choices of working fluids and pressure ratios were found to be very significant design parameters, together with selection of regenerator and source—sink heat transfer parameters. The parameter most influencing both the heating and cooling mode COPs and the heat transfer rates was found to be the heat conductance of the thermal sink.

Thermoelectric Cooling Analysis Using Modified-Graphical-Method for Multidimensional-Heat-Transfer-System

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Huy N. Phan ◽  
Dereje Agonafer
Keyword(s):  
Heat Transfer ◽  
Graphical Method ◽  
Cooling System ◽  
Coefficient Of Performance ◽  
Optimum Operating ◽  
Transfer System ◽  
Thermoelectric Coolers ◽  
Thermoelectric Modules ◽  
Active Cooling ◽  
Heat Transfer System

Comprehensive analysis of microelectronic cooling systems utilizing thermoelectric modules is time consuming because it involves solving many parametric equations, which require solving complex mathematical equations or the assistance of an expensive computation-fluid-dynamic software. In this study, a modified-graphical method (MGM) based on a previous study by Lineykin and Ben-Yaakov is proposed to analyze an active cooling system using thermoelectric modules. The MGM provides quicker visualization of the cooling requirement such as the optimum operating currents, temperature of the hot side, and coefficient of performance without the need of using any manufacturer’s proprietary data. In addition, the MGM is designed to analyze a multidimensional-heat-transfer-system utilizing thermoelectric modules (Phan, H., and Agonafer, D., 2010, “Experimental Analysis Model of an Active Cooling Method for 3D-ICs Utilizing Multidimensional Configured Thermoelectric Coolers,” ASME J. Electron. Packag. 132(2), p. 024501).

Heat transfer during spray/wall interaction with urea water solution: An experimental parameter study

2019 ◽  
Vol 78 ◽  
pp. 108432 ◽  
Author(s):  
David Schweigert ◽  
Björn Damson ◽  
Hartmut Lüders ◽  
Marion Börnhorst ◽  
Olaf Deutschmann
Keyword(s):  
Heat Transfer ◽  
Water Solution ◽  
Experimental Parameter ◽  
Parameter Study ◽  
Wall Interaction

scholarly journals Energy Savings of Simultaneous Heating and Cooling System According to Indoor Set Temperature Changes in the Comfort Range

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7691
Author(s):  
Dae-Uk Shin ◽  
Chang-Ho Jeong
Keyword(s):  
Heat Source ◽  
Energy Savings ◽  
Cooling System ◽  
Coefficient Of Performance ◽  
Energy Limit ◽  
Temperature Changes ◽  
Heating And Cooling ◽  
Small Load ◽  
Simultaneous Heating ◽  
Simultaneous Heating And Cooling

This study was conducted to derive the amount of energy savings when applying the method of making the load similar by changing the set temperature of the room in the building to which the simultaneous heating and cooling (SHC) system is applied. Energy savings were derived through theoretical analysis and comparisons through static simulations were performed to verify the proposed method. As a result, the energy savings are proportional to the energy limit that can be additionally input to the SHC and is proportional to the ratio of the coefficient of performance (COP) difference between the SHC and auxiliary heat source and the auxiliary heat source COP. That is, to increase the amount of energy savings, the maximum possible energy should be input for the SHC, or the SHC COP must be greater than the auxiliary heat source COP. In addition, comfort can be achieved stably by varying the set room temperature in a room with a small load. When a heat storage tank is installed or changing the indoor set temperature of both the hot and cold zones in real time by predicting the indoor load is possible, more energy can be saved.

Elastocaloric Cooling: System Design, Simulation, and Realization

2018 ◽  
Author(s):  
Felix Welsch ◽  
Susanne-Marie Kirsch ◽  
Nicolas Michaelis ◽  
Paul Motzki ◽  
Marvin Schmidt ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
System Design ◽  
Cooling System ◽  
Coefficient Of Performance ◽  
Transfer System ◽  
Vapor Compression ◽  
Cooling Systems ◽  
Elastocaloric Cooling ◽  
Heat Transfer System

Elastocaloric cooling is a novel environment-friendly alternative to vapor compression-based cooling systems. This solid-state cooling technology uses NiTi shape memory alloys (SMAs) as cooling medium. SMAs are well known for lightweight actuator systems and biomedical applications, but in addition, these alloys exhibit excellent cooling properties. Due to the high latent heats activated by mechanical loading/unloading, large temperature changes can be generated in the material. Accompanied by a small required work input, this also leads to a high coefficient of performance superior to vapor compression-based systems. In order to access the potential of these alloys, the development of suitable thermodynamic cooling cycles and an efficient system design are required. This paper presents a model-based design process of an elastocaloric air-cooling device. The device is divided into two parts, a mechanical system for continuously loading and unloading of multiple SMA wire bundles by a rotary motor and a heat transfer system. The heat transfer system enables an efficient heat exchange between the heat source and the SMA wires as well as between the SMA wires and the environment. The device operates without any additional heat transfer medium and cools the heat source directly, which is an advantage in comparison to conventional cooling systems. The design of this complex device in an efficient manner requires a model approach, capable of predicting the system parameters cooling power, mechanical work and coefficient of performance under various operating conditions. The developed model consists of a computationally efficient, thermo-mechanically coupled and energy based SMA model, a model of the system kinematics and a heat transfer model. With this approach, the complete cooling system can be simulated, and the required number of SMA wires as well as the mechanical power can be predicted in order to meet the system requirements. Based on the simulation results a first prototype of the elastocaloric cooling system is realized.

Thermal Hydraulics Analysis Under Natural Circulation Condition of the 4S

2010 ◽  
Author(s):  
Hisao Watanabe ◽  
Atsuko Matsuda ◽  
Jun Ohno
Keyword(s):  
Heat Transfer ◽  
Core Temperature ◽  
Cooling System ◽  
Natural Circulation ◽  
Air Flow ◽  
Parameter Analysis ◽  
Thermal Hydraulics ◽  
The Core ◽  
Radial Heat ◽  
Circulation Condition

Thermal hydraulics analysis under natural circulation condition of the 4S was performed with a 3 D total integrated model which contains the primary equipment in the reactor vessel (R/V), the intermediate equipment, the reactor auxiliary cooling system (RVACS), and the intermediate reactor auxiliary cooling system (IRACS). In the long term after the reactor trip, the primary coolant, the intermediate coolant, the RVACS air flow, and the IRACS air flow were circulated by natural circulation force. As the result, it has been confirmed that the core temperature was passively decreased gradually in a safe manner. The natural circulation force in the R/V is affected by temperature distribution in the R/V. In order to comprehend the effect of radial heat transfer in the R/V, it was shown the parameter analysis changed the radial heat transfer rate. As the result, the natural circulation flow decreases, as the radial heat transfer increase. On the other hand the core mean temperature decreases because the generated heat in the core was released to the core outer region. Regarding to the inner core temperature, it has tendency to increase.

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