Effects of Adsorbent Conductivity and Permeability on the Performance of a Solid Sorption Heat Pump

1999 ◽  
Vol 121 (1) ◽  
pp. 51-59 ◽  
Author(s):  
M. W. Ellis ◽  
W. J. Wepfer
Keyword(s):  
Thermal Conductivity ◽  
Heat Pump ◽  
Thermal Wave ◽  
Adsorption Equilibrium ◽  
Heat Pumps ◽  
Vapor Flow ◽  
Heating And Cooling ◽  
Improved Performance ◽  
Sorption Heat ◽  
Sorption Heat Pump

Solid sorption heat pumps can improve the effectiveness with which energy resources are used for heating and cooling. These systems operate by alternately heating and cooling beds of adsorbent material to produce a flow of refrigerant. The research presented here evaluates the effects of adsorbent thermal conductivity and permeability on the performance of a thermal wave solid sorption heat pump. In order to evaluate these effects, a numerical model of the thermal wave heat pump is developed. This model incorporates not only the effects of the conductivity and permeability, but also the effects of the adsorption equilibrium properties, refrigerant properties, application parameters, operating parameters, and bed geometry. For a typical air conditioning application, the model is used to study the influence of conductivity and permeability on the COP for systems using ammonia as a refrigerant. The results indicate that for the geometry considered, increasing the thermal conductivity of the adsorbent to 1 W/m-K can improve the COP to approximately 0.75. Further increases in conductivity do not yield improved performance. Furthermore, the reduced permeability associated with high conductivity adsorbents can impair vapor flow and lead to decreased performance.

Readsorption Processes in a Sorption Bed Heat Exchanger During Pressurization and Depressurization

1995 ◽  
Vol 117 (4) ◽  
pp. 865-870 ◽  
Author(s):  
W. Zheng ◽  
W. M. Worek
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Initial Temperature ◽  
The Other ◽  
Sorption Heat ◽  
Sorption Heat Pump

Readsorption occurs inside a sorbent-bed heat exchanger during the pressurization and depressurization processes, causing the adsorbate to be relocated from one end of the sorption bed heat exchanger to the other. In this paper, the readsorption processes are quantitatively determined for both the pressurization and depressurization processes in a sorbent-bed heat exchanger with a uniform initial temperature, loading, and pressure. Also, the readsorption that occurs during a typical operation of a two-bed sorption heat pump is quantified. The results show that the readsorption can cause as much as 30 percent of the ammonia in a sorbent-bed heat exchanger to be reallocated.

A Model for a Geothermal Well in a Hydraulic Groundwater Flow for Ground Source Heat Pump Systems

2011 ◽  
Author(s):  
Kevin D. Woods ◽  
Alfonso Ortega
Keyword(s):  
Thermal Conductivity ◽  
Analytical Solution ◽  
Groundwater Flow ◽  
Heat Pump ◽  
Temperature Response ◽  
Ambient Air ◽  
Heat Pumps ◽  
Thermal Reservoir ◽  
Geothermal Well ◽  
Ground Source

Heat pumps are mechanical systems that provide heating to a space in the winter, and cooling in the summer. They are increasingly popular because the same system provides both cooling modes, depending on the direction of the cycle upon which they operate. For proper operation, the heat pump must be connected to a constant temperature thermal reservoir which in traditional systems is the ambient air. In ground source heat pumps however, subterranean ground water is used as the thermal reservoir. To access the subterranean groundwater, “geothermal” wells are drilled into the formation. Water from the building heating or cooling system is circulated through the wells thereby promoting heat exchange between the coolant water and the subterranean formation. The potential for higher efficiency heating and cooling has increased the utilization of ground source heating ventilating and air conditioning systems. In addition, their compatibility with a naturally occurring and stable thermal reservoir has increased their use in the design of sustainable or green buildings and man-made environments. Groundwater flow affects the temperature response of thermal wells due to advection of heat by physical movement of groundwater through the aquifer. Research on this subject is scarce in the geothermal literature. This paper presents the derivation of an analytical solution for thermal dispersion by conduction and advection from hydraulic groundwater flow for a “geothermal” well. This analytical solution is validated against asymptotic analytical solutions. The traditional constant linear heat source solution is dependent on the ground formation thermal properties; the most dominant of which is the thermal conductivity. The results show that as hydraulic groundwater flow increases, the influence of the ground formation thermal conductivity on the temperature response of the well diminishes. The diminishing influence is evident in the Peclet number parameter; a comparison of thermal advection from hydraulic groundwater flow to thermal conduction by molecular diffusion.

scholarly journals Heat pump systems: A mini review

2021 ◽  
Vol 4 (2) ◽  
pp. 73-81
Author(s):  
Mohammad Omar Temori ◽  
František Vranay
Keyword(s):  
Heat Pump ◽  
Electricity Consumption ◽  
Cost Savings ◽  
Electrical Energy ◽  
Primary Energy ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Heating And Cooling ◽  
Ground Source ◽  
Reduce Electricity Consumption

In this work, a mini review of heat pumps is presented. The work is intended to introduce a technology that can be used to income energy from the natural environment and thus reduce electricity consumption for heating and cooling. A heat pump is a mechanical device that transfers heat from one environmental compartment to another, typically against a temperature gradient (i.e. from cool to hot). In order to do this, an energy input is required: this may be mechanical, electrical or thermal energy. In most modern heat pumps, electrical energy powers a compressor, which drives a compression - expansion cycle of refrigerant fluid between two heat exchanges: a cold evaporator and a warm condenser. The efficiency or coefficient of performance (COP), of a heat pump is defined as the thermal output divided by the primary energy (electricity) input. The COP decreases as the temperature difference between the cool heat source and the warm heat sink increases. An efficient ground source heat pump (GSHP) may achieve a COP of around 4. Heat pumps are ideal for exploiting low-temperature environmental heat sources: the air, surface waters or the ground. They can deliver significant environmental (CO2) and cost savings.

scholarly journals A European Database of Building Energy Profiles to Support the Design of Ground Source Heat Pumps

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2496 ◽  
Author(s):  
Laura Carnieletto ◽  
Borja Badenes ◽  
Marco Belliardi ◽  
Adriana Bernardi ◽  
Samantha Graci ◽  
...  
Keyword(s):  
Heat Pump ◽  
Energy Demand ◽  
Residential Buildings ◽  
Building Energy ◽  
Heat Pumps ◽  
Climatic Conditions ◽  
Ground Source Heat Pumps ◽  
Heating And Cooling ◽  
Energy Profiles ◽  
Ground Source

The design of ground source heat pumps is a fundamental step to ensure the high energy efficiency of heat pump systems throughout their operating years. To enhance the diffusion of ground source heat pump systems, two different tools are developed in the H2020 research project named, “Cheap GSHPs”: A design tool and a decision support system. In both cases, the energy demand of the buildings may not be calculated by the user. The main input data, to evaluate the size of the borehole heat exchangers, is the building energy demand. This paper presents a methodology to correlate energy demand, building typologies, and climatic conditions for different types of residential buildings. Rather than envelope properties, three insulation levels have been considered in different climatic conditions to set up a database of energy profiles. Analyzing European climatic test reference years, 23 locations have been considered. For each location, the overall energy and the mean hourly monthly energy profiles for heating and cooling have been calculated. Pre-calculated profiles are needed to size generation systems and, in particular, ground source heat pumps. For this reason, correlations based on the degree days for heating and cooling demand have been found in order to generalize the results for different buildings. These correlations depend on the Köppen–Geiger climate scale.

Pressure boost thermochemical sorption heat pump cycle

Energy ◽  
2019 ◽  
Vol 169 ◽  
pp. 1090-1100 ◽  
Author(s):  
Peng Gao ◽  
Liang-Liang Shao ◽  
Chun-Lu Zhang
Keyword(s):  
Heat Pump ◽  
Sorption Heat ◽  
Sorption Heat Pump
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