Ammonium Chloride (NH4Cl)—Ammonia (NH3): Sorption Characteristics for Heat Pump Applications

In a resorption heat pump, the adsorption and desorption reaction of ammonium chloride (NH4Cl) with ammonia (NH3) is of interest as a Low Temperature Salt (LTS). Reviewing previously published NH4Cl-NH3 equilibrium lines, ammonium chloride appears to offer useable working temperatures (50–70 °C) in the 10–15 bar pressure range during the adsorption reaction, and provides beneficial working conditions for the desorption reaction, when compared with alternative LTS candidates at atmospheric pressure. The NH4Cl-NH3 adsorption and desorption reactions, using a NH4Cl composite salt, have been evaluated under dynamic ‘real-world’ conditions in a Large Temperature Jump (LTJ) experimental testing rig; although there are concerns with mass transfer characteristics, the salt exhibits no hysteresis between the adsorption and desorption reactions, contrary to previous literature. The experimentally obtained equilibrium line values for the reaction enthalpy and entropy are 29,835 J/mol and 207 J/(mol∙K), respectively. Using a semi-empirical model, the NH4Cl composite salt has been successfully characterised, enabling the prediction of salt reaction behaviour. The model constants, A and n, identified are 4.5 and 5 for adsorption and 5 and 4 for desorption, with an overall salt active fraction (applicable to both reactions) of 0.98. Overall, the working equilibrium line and the dynamic performance of ammonium chloride has been investigated and the applicability of NH4Cl as a LTS for a resorption heat pump determined.

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Design and Experimental Testing of a Ground Source Heat Pump System Based on Energy-Saving Solar Collector

Journal of Energy Engineering ◽

10.1061/(asce)ey.1943-7897.0000288 ◽

2016 ◽

Vol 142 (3) ◽

pp. 04015022 ◽

Cited By ~ 5

Author(s):

Zhitao Zheng ◽

Ying Xu ◽

Jianghui Dong ◽

Linfang Zhang ◽

Liping Wang

Keyword(s):

Energy Saving ◽

Heat Pump ◽

Solar Collector ◽

Experimental Testing ◽

Ground Source Heat Pump ◽

Pump System ◽

Heat Pump System ◽

Ground Source

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Effects of compressor frequency and heat exchanger geometry on dynamic performance characteristics of heat pump dryers

Energy ◽

10.1016/j.energy.2021.121391 ◽

2021 ◽

pp. 121391

Author(s):

JunYoung Choi ◽

DongChan Lee ◽

Myeong Hyen Park ◽

Yongju Lee ◽

Yongchan Kim

Keyword(s):

Heat Exchanger ◽

Heat Pump ◽

Dynamic Performance ◽

Performance Characteristics

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Theoretical investigation on the heating performance of a recuperative heat pump water heater using CO2/HCs with large temperature glides in cold regions

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4052599 ◽

2021 ◽

pp. 1-22

Author(s):

Jielin Luo ◽

Qin Wang ◽

Zhen Zhao ◽

Kaiyin Yang ◽

Guangming Chen ◽

...

Keyword(s):

Heat Pump ◽

Temperature Difference ◽

Hot Water ◽

Large Temperature ◽

Water Heater ◽

Ambient Temperatures ◽

Heating Performance ◽

Heat Pump Water Heater ◽

Vapor Injection ◽

Injection Cycle

Abstract Considering the issues of environmental pollution and energy efficiency, heat pumps are gradually replacing traditional coal combustion for heating at low ambient temperatures. In this paper, eco-friendly CO2/HCs with large temperature glides are applied in a single-stage recuperative heat pump water heater. Its heating performance is theoretically investigated under the working condition of producing circulating hot water in typical winter of northern China, with medium temperature difference between supply/return water and large temperature difference between air inlet and water inlet. Due to its simple structure, low initial investment and high efficiency, its potential for producing circulating hot water is demonstrated. Exergy analyses are conducted to reveal the significant influence of the exergy losses of heat exchanger on system performance. For specified CO2/HC, optimal COP is obtained through global optimization of cycle pressures and mixture concentration. The heating performances of different CO2/HCs are compared, among which CO2/R600 and CO2/R600a behave better. Meanwhile, a typical vapor-injection cycle is used to demonstrate priorities on the heating performance of this recuperative cycle, in which the COP of recuperative cycle using CO2/R600 is more than 3.4% higher than that of the vapor-injection cycle. The results obtained in this paper provide a simple and efficient solution for producing circulating hot water at low ambient temperatures.

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Dynamic performance of a prototype solar-assisted heat pump

10.2172/5285312 ◽

1981 ◽

Author(s):

M. Catan

Keyword(s):

Heat Pump ◽

Dynamic Performance

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Critical Analysis of Process Integration Options for Joule-Cycle and Conventional Heat Pumps

Energies ◽

10.3390/en13030635 ◽

2020 ◽

Vol 13 (3) ◽

pp. 635 ◽

Cited By ~ 1

Author(s):

Limei Gai ◽

Petar Sabev Varbanov ◽

Timothy Gordon Walmsley ◽

Jiří Jaromír Klemeš

Keyword(s):

Heat Pump ◽

Process Integration ◽

Waste Heat ◽

Correct Choice ◽

Heat Pumps ◽

Coefficient Of Performance ◽

Large Temperature ◽

Temperature Changes ◽

Application Range ◽

Source And Sink

To date, research on heat pumps (HP) has mainly focused on vapour compression heat pumps (VCHP), transcritical heat pumps (TCHP), absorption heat pumps, and their heat integration with processes. Few studies have considered the Joule cycle heat pump (JCHP), which raises several questions. What are the characteristics and specifics of these different heat pumps? How are they different when they integrate with the processes? For different processes, which heat pump is more appropriate? To address these questions, the performance and integration of different types of heat pumps with various processes have been studied through Pinch Methodology. The results show that different heat pumps have their own optimal application range. The new JCHP is suitable for processes in which the temperature changes of source and sink are both massive. The VCHP is more suitable for the source and sink temperatures, which are near-constant. The TCHP is more suitable for sources with small temperature changes and sinks with large temperature changes. This study develops an approach that provides guidance for the selection of heat pumps by applying Process Integration to various combinations of heat pump types and processes. It is shown that the correct choice of heat pump type for each application is of utmost importance, as the Coefficient of Performance can be improved by up to an order of magnitude. By recovering and upgrading process waste heat, heat pumps can save 15–78% of the hot utility depending on the specific process.

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Simulation analysis on dynamic performance of a combined solar/air dual source heat pump water heater

Energy Conversion and Management ◽

10.1016/j.enconman.2016.04.102 ◽

2016 ◽

Vol 120 ◽

pp. 378-387 ◽

Cited By ~ 39

Author(s):

Weishi Deng ◽

Jianlin Yu

Keyword(s):

Heat Pump ◽

Simulation Analysis ◽

Dynamic Performance ◽

Water Heater ◽

Heat Pump Water Heater ◽

Dual Source

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Experimental Analysis of an Air Heat Pump for Heating Service Using a “Hardware-In-The-Loop” System

Energies ◽

10.3390/en13174498 ◽

2020 ◽

Vol 13 (17) ◽

pp. 4498 ◽

Cited By ~ 1

Author(s):

Paolo Conti ◽

Carlo Bartoli ◽

Alessandro Franco ◽

Daniele Testi

Keyword(s):

Heat Pump ◽

Dynamic Performance ◽

Plant Performance ◽

Coefficient Of Performance ◽

Weather Data ◽

Hardware In The Loop ◽

Pump System ◽

Heat Pump System ◽

Experimental Campaign ◽

Experimental Apparatus

Estimating and optimizing the dynamic performance of a heat pump system coupled to a building is a paramount yet complex task, especially under intermittent conditions. This paper presents the “hardware-in-the-loop” experimental campaign of an air-source heat pump serving a typical dwelling in Pisa (Italy). The experimental apparatus uses real pieces of equipment, together with a thermal load emulator controlled by a full energy dynamic simulation of the considered building. Real weather data are continuously collected and used to run the simulation. The experimental campaign was performed from November 2019 to February 2020, measuring the system performances under real climate and load dynamics. With a water set point equal to 40 °C, the average heat pump coefficient of performance was about 3, while the overall building-plant performance was around 2. The deviation between the two performance indexes can be ascribed to the continuous on-off signals given by the zone thermostat due to the oversized capacity of the heat emission system. The overall performance raised to 2.5 thanks to a smoother operation obtained with reduced supply temperature (35 °C) and fan coil speed. The paper demonstrates the relevance of a dynamic analysis of the building-HVAC system and the potential of the “hardware-in-the-loop” approach in assessing actual part-load heat pump performances with respect to the standard stationary methodology.

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Dynamic Performance of an Oil Starved Squeeze Film Damper Combined With a Cylindrical Roller Bearing

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4042418 ◽

2019 ◽

Vol 141 (7) ◽

Author(s):

H. Meeus ◽

J. Fiszer ◽

G. Van De Velde ◽

B. Verrelst ◽

D. Lefeber ◽

...

Keyword(s):

Failure Modes ◽

Experimental Testing ◽

Mechanical Energy ◽

Dynamic Performance ◽

Roller Bearing ◽

Dynamic Test ◽

Nonlinear Behavior ◽

High Amplitude ◽

Squeeze Film ◽

Highly Nonlinear

Squeeze film dampers (SFDs) are widely used to dissipate mechanical energy caused by rotor vibrations as well as to improve overall stability of the rotor system. Especially turbomachine rotors, supported on little damped rolling element bearings (REBs), are primarily sensitive to unbalance excitation and thus high amplitude vibrations. To ensure safe operation, potential failure modes, such as an oil starved damper state, need to be well examined prior to the introduction in the ultimate industrial application. Hence, the aim of this research project is to evaluate the performance of the rotor support for a complete oil starvation of the SFD. An academic rotor dynamic test bench has been developed and briefly presented. Experimental testing has been conducted for two static radial load cases resembling the full load and idle condition of a certain turbomachine. Evidently, the measurement results exposed severe vibration problems. Even a split first whirl mode arises due to a pronounced anisotropic bearing stiffness. Moreover, for the least radially loaded bearing, highly nonlinear behavior emerged at elevated unbalance excitation. Consequently, the rollers start to rattle which will have a negative effect on the overall bearing lifetime. To explain the nature of the nonlinear behavior, advanced quasi-static bearing simulations are exploited. A number of possible solutions are proposed in order to help mitigate the vibration issues.

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