scholarly journals Performance estimation of membrane dehumidification based on heat exchanger analogy approaches using ε-NTU model

2020 ◽  
Vol 15 (2) ◽  
pp. 299-307
Author(s):  
Gilbong Lee ◽  
Chul Woo Roh ◽  
Bong Soo Choi ◽  
Eunseok Wang ◽  
Ho-Sang Ra ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Cooling System ◽  
Design Guidelines ◽  
Performance Estimation ◽  
Department Of Energy ◽  
Dew Point ◽  
Design Parameters ◽  
Evaporator Temperature ◽  
Vapour Compression

Abstract Reports by the US Department of Energy in 2014 evaluated membrane heat pump technology as one of the most promising alternatives to conventional vapour compression methods. Vapour compression methods maintain an evaporator temperature lower than the dew point to deal with the latent heat load. In membrane heat pump systems, only the water vapour is transferred and there is no phase change. The migration is caused by the difference in vapour pressure before and after the membrane. A vacuum pump or blower is used to create the pressure difference. However, there is no methodology for predicting dehumidification performance of membranes when used as part of a cooling system. In this study, using the assumption that there is a similarity between heat transfer and moisture pervaporation, the performance indices of the membrane are derived using a well-known heat exchanger method, the ε-NTU models. Performance estimations are calculated for two representative system layouts: bypass and vacuum. Simple relations between design parameters are suggested, giving design guidelines for researchers.

Economics of Gas Turbine Inlet Air Cooling System for Power Enhancement

1996 ◽  
Author(s):  
Motoaki Utamura ◽  
Yoshio Nishimura ◽  
Akira Ishikawa ◽  
Nobuo Ando
Keyword(s):  
Power Generation ◽  
Thermal Energy ◽  
Cooling System ◽  
Electric Energy ◽  
Dew Point ◽  
Design Parameters ◽  
Air Cooling ◽  
Power Enhancement ◽  
Air Cooling System ◽  
Running Cost

A cost estimate method is presented, which enables to compare inlet air cooling system for power enhancement of combustion turbine with other power generation system. A new energy conversion index is developed which arranges system design parameters in a dimensionless form and also exhibits running cost. It is suggested that the inlet air cooling system is equivalent to simple cycle or pumped storage in view of the dimensionless running cost. Next, a cost diagram relating capital cost to power generation cost is presented also in non-dimensional form, which could provide a measure to examine investment worth for a power producer. Moreover, cooling effectiveness as function of cooled inlet air temperature is investigated using specific thermal energy. It is revealed that cooling beyond dew point requires a larger thermal energy per electric energy produced and thus less economical unless the price of electricity depends on electricity demand.

Analysis of the efficiency of hydrocarbon propellant cooling using liquid nitrogen and a combination of recuperative heat exchangers

2020 ◽  
Author(s):  
A.A. Aleksandrov ◽  
I.V. Barmin ◽  
A.V. Zolin ◽  
V.V. Chugunkov
Keyword(s):  
Heat Exchanger ◽  
Liquid Nitrogen ◽  
Coming Out ◽  
Heat Exchangers ◽  
Cooling System ◽  
Design Parameters ◽  
Nitrogen Gas ◽  
Double Pipe ◽  
The Cost ◽  
Pipe Heat

The paper describes the propellant cooling system using liquid nitrogen and a combination of recuperative heat exchangers, including sections of the double pipe heat exchanger and a twisted heat exchanger located in a tank with antifreeze, cooled by nitrogen gas coming out of the sections of the double pipe heat exchanger. Mathematical models of cooling processes for two variants of movement of propellant and liquid nitrogen in the channels of the double pipe heat exchanger sections are considered. Their using makes it possible to analyze the efficiency of propellant cooling operations depending on its mass, design parameters of the system tanks and heat exchangers, consumption characteristics of nitrogen and propellant, as well as to predict the required mass of liquid nitrogen and the time of propellant cooling during the operation of launching complex propellant-feed systems. Calculated dependences and simulation results of propellant and antifreeze cooling in a tank with a twisted heat exchanger are presented. The influence of variants of arranging propellant cooling processes and liquid nitrogen consumption on the efficiency of the cooling system is analyzed. Comparing to the available systems the capability of reducing the cost of liquid nitrogen are identified as well as reducing time of the propellant cooling operations by means of equipping launch complexes.

scholarly journals Design of a Heat Pump Based Heater and Dehumidifier Device

2019 ◽  
Vol 14 (1) ◽  
pp. 111-121
Author(s):  
Ákos Pozsa ◽  
Tamás Illés ◽  
Károly Marcell Mészáros ◽  
Norbert Szaszák ◽  
Péter Bencs
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
High Efficiency ◽  
Residential Building ◽  
Absolute Humidity ◽  
Dew Point ◽  
Heat Extraction ◽  
Heating Efficiency ◽  
The Absolute ◽  
Very High

Many residential building use electrical heaters mainly in bathrooms, even as a supplement heating device. These devices typically operate at very high efficiency, since in most cases, electrical current is converted into Joule-heat by means of electrical resistances. The humidity of the air in bathrooms is often very high. Therefore, it would be useful to apply such heating devices, which not only increase the temperature of the air, but also reduces the absolute humidity of it. If a heat pump is used for heating purposes where both the heat absorber and the heat exchanger are placed in the same airspace, condensation occurs at a temperature below the dew point of the given air condition at the point of heat extraction thus some of the humidity precipitates. Along with this the absolute humidity of the air can be reduced (which is also recommended for hygiene reasons). Furthermore, due to the latent heat released during the condensation a significant excess of heat appears on the heat exchanger, increasing the heating efficiency over 100%. The design and operation of a heat pump heater operating on such a principle is described in this study, addressing the typical air-conditioning parameters, correlations, calculations performed for the design.

Mesoscopic Heat-Actuated Heat Pump Development

1999 ◽  
Author(s):  
Kevin Drost
Keyword(s):  
Mass Transfer ◽  
Heat Exchanger ◽  
Pacific Northwest ◽  
Heat Pump ◽  
Cooling System ◽  
High Heat ◽  
Absorption Heat Pump ◽  
Transfer Rates ◽  
Alternative Systems ◽  
Air Cooled Heat Exchanger

Abstract Battelle, Pacific Northwest Division (Battelle) and Pacific Northwest National Laboratory1 (PNNL) are developing a miniature absorption heat pump. Targeted applications include microclimate control ranging from manportable cooling to distributed space conditioning. The miniature absorption heat pump will be sized to provide 350 Wt of cooling2. A complete manportable cooling system, which will include the microscale heat pump, an air-cooled heat exchanger, batteries, and fuel, is estimated to weigh between 4 and 5 kg. For comparison, alternative systems weigh about 10 kg. Size and weight reductions in the microscale heat pump are possible because the device can take advantage of the high heat and mass transfer rates attainable in microscale structures.

Development of a Novel Two-Stage Heat Pump Clothes Dryer

2014 ◽  
Author(s):  
Tao Cao ◽  
Jiazhen Ling ◽  
Yunho Hwang ◽  
Reinhard Radermacher
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Energy Savings ◽  
Design Tool ◽  
Department Of Energy ◽  
Two Stage ◽  
Heat Exchanger Design ◽  
Clothes Dryer ◽  
Vapor Injection ◽  
Injection Cycle

An energy efficient two-stage heat pump clothes dryer (HPCD) was successfully developed. This new dryer utilizes three advanced technologies: vapor injection cycle, compact heat exchanger and brushless direct current (BLDC) fan motor. An in-house heat exchanger design tool – CoilDesigner was utilized to design and optimize the evaporator and condenser in the vapor injection cycle. One electric clothes dryer (CD) from U.S. market was selected as the baseline product, and one hybrid HPCD from European market was selected as the best state-of-the-art commercial product in terms of energy efficiency. These two commercial products and the constructed two-stage HPCD prototype were tested according to the Department of Energy (DOE) dryer test standards. Experimental evaluation revealed that the two-stage HPCD achieved 59% energy savings and improved energy factor (EF) by 143% as compared to the electric dryer. It also achieved 25% energy savings and improved EF by 33% as compared to the hybrid HPCD. This implied that the two-stage HPCD could save energy up to 42 TW·h annually if this technology is fully deployed to replace all U.S. electric CDs. Cost analysis indicates that the payback period of the two-stage HPCD is only 2.2 years as compared to the electric dryer with bottom cabinet. Therefore, the two-stage HPCD is an economically competitive greener option.

scholarly journals Testing of a Radiant Wall Cooling System with Pipes Coupled to Aerated Blocks

2021 ◽  
Author(s):  
Martin Šimko ◽  
Dušan Petráš ◽  
Michal Krajčík ◽  
Daniel Szabó
Keyword(s):  
Surface Temperature ◽  
Cooling System ◽  
Thermal Response ◽  
Cooling Capacity ◽  
Climatic Conditions ◽  
Dew Point ◽  
Outdoor Environment ◽  
Design Parameters ◽  
Indoor Climate ◽  
Thermal Output

Thermal output, surface temperatures, and supply and return water temperature were measured for a wall cooling system involving pipe attached to a wall section made of thermally insulating blocks. The experiment was performed for warm climatic conditions typical of, e.g., summer in Central and Northern Europe. The outdoor environment was simulated by a climatic chamber while the indoor climate was simulated by attaching a hotbox to the wall surface. The sensitivity of thermal output to several design parameters was investigated by 2D numerical simulations. The measurements showed a fast thermal response of the wall system. The cooling output was 38.3 W per m2 of the cooling area which equalled about 4.8 W/m2 per 1 K temperature difference between water and hotbox. The lowest surface temperature of 19.6 °C was measured at the pipe. Thus, the cooling output could be enhanced by reducing the surface temperature closer to the dew point temperature. The temperature of water in the pipe was very close to the surface temperature. It was illustrated how this characteristic of the wall cooling system tested positively affects the efficiency and cooling capacity of an air-to-water heat pump.

scholarly journals Interpretation of rock mass thermal conductivity at the design stage of heat pump installation and its impact on system efficiency (COP)

2018 ◽  
Vol 66 ◽  
pp. 02007
Author(s):  
Michał Kaczmarczyk ◽  
Magda Kaczmarczyk ◽  
Konrad Thürmer ◽  
Magdalena Klich
Keyword(s):  
Thermal Conductivity ◽  
Rock Mass ◽  
Heat Exchanger ◽  
Heat Pump ◽  
Cooling System ◽  
Thermal Power ◽  
Economic Effect ◽  
Thermal Conditions ◽  
Design Stage ◽  
Ground Source

The recognition of geological and thermal conditions of the rock mass in the case of designing a vertical borehole heat exchanger as the ground source for heat pump installations is a key issue affecting the efficiency of the heating/cooling system operation. This is especially important for large-sized buildings with a high demand for thermal power, which affects into the size of the ground source installation. The aim of the article is to indicate the difference in the obtained results concerning thermal calculations at the design stage of the brine/water heat pump installation with the vertical heat exchanger, in relation to the theoretical values of the rock mass thermal conductivity and the real (measured) values obtained during the thermal response test (TRT). For this purpose, calculations of thermal efficiency from one meter of the current rock mass were made, with particular emphasis on the change in the value of the thermal conductivity coefficient in the tested drilling profiles. Correspondingly, heat pump coefficients of performance (COP) were calculated, which allowed to analyze the influence of the over/undersizing phenomenon of the ground source on the technical parameters of the heat pump's operation and the economic effect of the investment.

scholarly journals Utilization of the horizontal ground heat exchanger in the heating and cooling system of a residential building

2016 ◽  
Vol 37 (1) ◽  
pp. 47-72 ◽  
Author(s):  
Małgorzata Hanuszkiewicz-Drapała ◽  
Tomasz Bury
Keyword(s):  
Heat Exchanger ◽  
Heat Source ◽  
Heat Pump ◽  
Cooling System ◽  
Electricity Consumption ◽  
Residential Building ◽  
Heat Fluxes ◽  
Winter Period ◽  
Ground Heat Exchanger ◽  
The Impact

AbstractThis paper presents the results of thermodynamic analyses of a system using a horizontal ground heat exchanger to cool a residential building in summer and heat it in the autumn-winter period. The main heating device is a vapour compression heat pump with the ground as the lower heat source. The aim of the analyses is to examine the impact of heat supply to the ground in the summer period, when the building is cooled, on the operation of the heating system equipped with a heat pump in the next heating season, including electricity consumption. The processes occurring in cooling and heating systems have an unsteady nature. The main results of the calculations are among others the time-dependent values of heat fluxes extracted from or transferred to the ground heat exchanger, the fluxes of heat generated by the heat pump and supplied to the heated building by an additional heat source, the parameters in characteristic points of the systems, the temperature distributions in the ground and the driving electricity consumption in the period under analysis. The paper presents results of analysis of cumulative primary energy consumption of the analyzed systems and cumulative emissions of harmful substances.

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