Ramp Wave Analysis of the Solid/Vapor Heat Pump

1990 ◽  
Vol 112 (1) ◽  
pp. 69-78 ◽  
Author(s):  
S. V. Shelton ◽  
W. J. Wepfer ◽  
D. J. Miles
Keyword(s):  
Heat Transfer ◽  
Heat Pump ◽  
Thermal Wave ◽  
Wave Model ◽  
Heat Transfer Fluid ◽  
Cycle Performance ◽  
Pump System ◽  
Square Wave ◽  
Vapor Adsorption ◽  
Heating And Cooling

A theramlly driven heat pump using a solid/vapor adsorption/desorption compression process in a vapor compression cycle is thermodynamically analyzed. The cycle utilizes a simple heat transfer fluid circulating loop for heating and cooling of two solid adsorbent beds. This heat transfer fluid loop also serves to transmit heat recovered from the adsorbing bed being cooled to the desorbing bed being heated. This heat recovery process greatly improves the efficiency of the single-stage solid/vapor adsorption process without the complication of a two-stage cycle. During the heating and cooling processes a thermal wave profile travels through the beds. Previous studies of this cycle used a square wave model to simulate the thermal wave front. This paper utilizes a more physically realistic ramp wave model to overcome the shortcomings of the square wave model. The ramp wave model is integrated into a thermodynamic cycle which provides detailed information on the performance of the beds as well as the COP and the heating and cooling outputs of the heat pump system. Significant cycle design and operating parameters are varied to determine their effect on cycle performance.

Buildings

2017 ◽  
Author(s):  
Peter Rez
Keyword(s):  
Heat Transfer ◽  
Heat Pump ◽  
Energy Efficient ◽  
Energy Use ◽  
Fossil Fuel ◽  
Local Climate ◽  
Heating And Cooling ◽  
The Difference ◽  
As If

Most of the energy used by buildings goes into heating and cooling. For small buildings, such as houses, heat transfer by conduction through the sides is as much as, if not greater than, the heat transfer from air exchanges with the outside. For large buildings, such as offices and factories, the greater volume-to-surface ratio means that air exchanges are more significant. Lights, people and equipment can make significant contributions. Since the energy used depends on the difference in temperature between the inside and the outside, local climate is the most important factor that determines energy use. If heating is required, it is usually more efficient to use a heat pump than to directly burn a fossil fuel. Using diffuse daylight is always more energy efficient than lighting up a room with artificial lights, although this will set a limit on the size of buildings.

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.

scholarly journals Analysis and Comparison of Some Low-Temperature Heat Sources for Heat Pumps

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1853 ◽  
Author(s):  
Pavel Neuberger ◽  
Radomír Adamovský
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Heat Source ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Ambient Air ◽  
Heat Transfer Fluid ◽  
Heat Sources ◽  
Ground Heat Exchangers ◽  
Temperature Heat

The efficiency of a heat pump energy system is significantly influenced by its low-temperature heat source. This paper presents the results of operational monitoring, analysis and comparison of heat transfer fluid temperatures, outputs and extracted energies at the most widely used low temperature heat sources within 218 days of a heating period. The monitoring involved horizontal ground heat exchangers (HGHEs) of linear and Slinky type, vertical ground heat exchangers (VGHEs) with single and double U-tube exchanger as well as the ambient air. The results of the verification indicated that it was not possible to specify clearly the most advantageous low-temperature heat source that meets the requirements of the efficiency of the heat pump operation. The highest average heat transfer fluid temperatures were achieved at linear HGHE (8.13 ± 4.50 °C) and double U-tube VGHE (8.13 ± 3.12 °C). The highest average specific heat output 59.97 ± 41.80 W/m2 and specific energy extracted from the ground mass 2723.40 ± 1785.58 kJ/m2·day were recorded at single U-tube VGHE. The lowest thermal resistance value of 0.07 K·m2/W, specifying the efficiency of the heat transfer process between the ground mass and the heat transfer fluid, was monitored at linear HGHE. The use of ambient air as a low-temperature heat pump source was considered to be the least advantageous in terms of its temperature parameters.

scholarly journals Reconstruction of the thermal properties in a wave-type model of bio-heat transfer

2020 ◽  
Vol 30 (12) ◽  
pp. 5143-5167
Author(s):  
Moataz Alosaimi ◽  
Daniel Lesnic ◽  
Jitse Niesen
Keyword(s):  
Heat Transfer ◽  
Physical Properties ◽  
Thermal Wave ◽  
Wave Model ◽  
Temperature Measurements ◽  
Dimensionless Parameters ◽  
Content Type ◽  
Boundary Temperature ◽  
Dimensional Parameters ◽  
Thermo Physical Properties

Purpose This study aims to at numerically retrieve five constant dimensional thermo-physical properties of a biological tissue from dimensionless boundary temperature measurements. Design/methodology/approach The thermal-wave model of bio-heat transfer is used as an appropriate model because of its realism in situations in which the heat flux is extremely high or low and imposed over a short duration of time. For the numerical discretization, an unconditionally stable finite difference scheme used as a direct solver is developed. The sensitivity coefficients of the dimensionless boundary temperature measurements with respect to five constant dimensionless parameters appearing in a non-dimensionalised version of the governing hyperbolic model are computed. The retrieval of those dimensionless parameters, from both exact and noisy measurements, is successfully achieved by using a minimization procedure based on the MATLAB optimization toolbox routine lsqnonlin. The values of the five-dimensional parameters are recovered by inverting a nonlinear system of algebraic equations connecting those parameters to the dimensionless parameters whose values have already been recovered. Findings Accurate and stable numerical solutions for the unknown thermo-physical properties of a biological tissue from dimensionless boundary temperature measurements are obtained using the proposed numerical procedure. Research limitations/implications The current investigation is limited to the retrieval of constant physical properties, but future work will investigate the reconstruction of the space-dependent blood perfusion coefficient. Practical implications As noise inherently present in practical measurements is inverted, the paper is of practical significance and models a real-world situation. Social implications The findings of the present paper are of considerable significance and interest to practitioners in the biomedical engineering and medical physics sectors. Originality/value In comparison to Alkhwaji et al. (2012), the novelty and contribution of this work are as follows: considering the more general and realistic thermal-wave model of bio-heat transfer, accounting for a relaxation time; allowing for the tissue to have a finite size; and reconstructing five thermally significant dimensional parameters.

scholarly journals Exergoeconomic optimization of solar heat pump systems of heat supply

2020 ◽  
Vol 216 ◽  
pp. 01125
Author(s):  
Mexriya Koroly ◽  
Anvar Anarbaev ◽  
Alisher Usmanov ◽  
Kuvondyk Soliev
Keyword(s):  
Heat Pump ◽  
High Reliability ◽  
High Energy ◽  
Economic Optimization ◽  
Water Heater ◽  
Pump System ◽  
Heat Pump System ◽  
Solar Heat ◽  
Heating And Cooling ◽  
Industrial Heating

In this paper, there is analyzed the results of exergy economic optimization of heat-cooling supply in building by using the solar heat pump system. It is possible to realize a system having high reliability in operation of the system. The solar heat pump system according to the present technical decision has high energy efficiency while ensuring reliability, and is useful as a domestic air conditioning and heating water heater. It can also be applied to uses such as industrial heating and cooling devices.

Study on Cooling Heat Transfer of Supercritical Carbon Dioxide Applied to Transcritical Carbon Dioxide Heat Pump

2021 ◽  
pp. 451-493
Author(s):  
Chaobin Dang ◽  
Eiji Hihara
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Pump ◽  
Supercritical Co2 ◽  
Lubricating Oil ◽  
Cross Sectional ◽  
Pump System ◽  
Heat Pump System ◽  
Transcritical Carbon Dioxide ◽  
Supercritical Water Cooled Reactor

Understanding the heat transfer characteristics of supercritical fluids is of fundamental importance in many industrial processes such as transcritical heat pump system, supercritical water-cooled reactor, supercritical separation, and supercritical extraction processes. This chapter addresses recent experimental, theoretical, and numerical studies on cooling heat transfer of supercritical CO2. A systematic study on heat transfer coefficient and pressure drop of supercritical CO2 was carried out at wide ranges of tube diameter, mass flux, heat flux, temperature, and pressure. Based on the understanding of temperature and velocity distributions at cross-sectional direction provided by the numerical simulation, a new prediction model was proposed, which agreed well with the experimental results. In addition, the effect of lubricating oil was also discussed with the focus on the change in flow pattern and heat transfer performance of oil and supercritical CO2.

scholarly journals Performance and Exergy Transfer Analysis of Heat Exchangers with Graphene Nanofluids in Seawater Source Marine Heat Pump System

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1762 ◽  
Author(s):  
Zhe Wang ◽  
Fenghui Han ◽  
Yulong Ji ◽  
Wenhua Li
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Transfer Model ◽  
Enhanced Heat Transfer ◽  
Pump System ◽  
Heat Pump System ◽  
Tube Heat Exchanger ◽  
Exergy Transfer

A marine seawater source heat pump is based on the relatively stable temperature of seawater, and uses it as the system’s cold and heat source to provide the ship with the necessary cold and heat energy. This technology is one of the important solutions to reduce ship energy consumption. Therefore, in this paper, the heat exchanger in the CO2 heat pump system with graphene nano-fluid refrigerant is experimentally studied, and the influence of related factors on its heat transfer enhancement performance is analyzed. First, the paper describes the transformation of the heat pump system experimental bench, the preparation of six different mass concentrations (0~1 wt.%) of graphene nanofluid and its thermophysical properties. Secondly, this paper defines graphene nanofluids as beneficiary fluids, the heat exchanger gains cold fluid heat exergy increase, and the consumption of hot fluid heat is heat exergy decrease. Based on the heat transfer efficiency and exergy efficiency of the heat exchanger, an exergy transfer model was established for a seawater source of tube heat exchanger. Finally, the article carried out a test of enhanced heat transfer of heat exchangers with different concentrations of graphene nanofluid refrigerants under simulated seawater constant temperature conditions and analyzed the test results using energy and an exergy transfer model. The results show that the enhanced heat transfer effect brought by the low concentration (0~0.1 wt.%) of graphene nanofluid is greater than the effect of its viscosity on the performance and has a good exergy transfer effectiveness. When the concentration of graphene nanofluid is too high, the resistance caused by the increase in viscosity will exceed the enhanced heat transfer gain brought by the nanofluid, which results in a significant decrease in the exergy transfer effectiveness.

scholarly journals Experimental performance analysis of a multiple-source and multiple-use heat pump system: winter field experiment and heating operation performance evaluation

2019 ◽  
Vol 111 ◽  
pp. 01076 ◽  
Author(s):  
Mingzhe Liu ◽  
Ryozo Ooka ◽  
Toshiyuki Hino ◽  
Ke Wen ◽  
Wonjun Choi ◽  
...  
Keyword(s):  
Field Experiment ◽  
Heat Pump ◽  
System Performance ◽  
Multiple Source ◽  
Stable Operation ◽  
Multiple Use ◽  
Operation Performance ◽  
Pump System ◽  
Heat Pump System ◽  
Heating And Cooling

We herein report the development of a distributed heat pump system that can utilize a variety of renewable energy sources to meet different building heating and cooling demands (i.e., a multiple source and multiple use heat pump system, MMHP). In this system, a water circulating loop is used to connect ground heat exchangers, a unique sky-source heat pump, and various heat pumps for heating and cooling purposes to form a thermal network within a building. This distribution increases the flexibility of the system and allows an improved matching of supply and demand. To evaluate the system performance, an experimental house was constructed, and a winter field experiment was conducted. We found that the reported heat pump for floor heating achieved a stable operation with a high coefficient of performance of ~11.5, while the heat collecting operation performance of the sky-source heat pump varied significantly depending on the amount of solar radiation and the outside air temperature. Finally, since the sky-source heat pump contributes to an improvement in the whole system performance, it appears that there is still room for improved regarding the whole system performance by adjusting the operating and control strategy.

Characteristics Study of Sewage Source Heat Pump System Based on Heat Transfer Enhancement and Acoustic Cavitation Decontamination

2014 ◽  
Vol 665 ◽  
pp. 607-610
Author(s):  
Jian Feng Qian ◽  
Ya Yuan Liu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Heat Pump ◽  
Treatment Time ◽  
Acoustic Cavitation ◽  
Ultrasonic Cavitation ◽  
Transfer Enhancement ◽  
Pump System ◽  
Heat Pump System ◽  
Sewage Source

Put forward an application of ultrasonic cavitation technology of the sewage source heat pump system to solve the problem of controlling pollution and emphatically discusses the principle of acoustic cavitation and the effect, to conduct a feasibility analysis of Anti-fouling in sewage source heat pump sewage side. Through analysis principle of ultrasonic cavitation and heat transfer enhancement for carrying the experiment, study the pattern of scaling in heat exchange tube for different velocity and viscosity, effect in flow rate on the ultrasonic cleaning wastewater, Effect in ultrasonic treatment time on the descaling result. Obtain that it can enhancement transfer for 48%.

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