Analysis of Regional Suitability of the Ground-Coupled Heat Pump Based on the Shallow Ground Thermal Balance

2009 ◽  
Author(s):  
Yuefen Gao ◽  
Songling Wang ◽  
Guoqiang Zhang
Keyword(s):  
Heat Source ◽  
Heat Pump ◽  
Heat Pumps ◽  
Scientific Application ◽  
Term Operation ◽  
Ground Heat Exchangers ◽  
Ground Coupled Heat Pumps ◽  
Ground Coupled Heat Pump ◽  
Consistent Performance ◽  
Source And Sink

Ground-coupled heat pump systems use the ground as a heat source and sink either with vertical or horizontal ground heat exchangers (GHXs) to supply heating in winter and cooling in summer. The ground heat source and sink has a near constant temperature, which is well suited to ground-coupled heat pumps, giving them consistent performance, regardless of the outdoor temperature. However, when the heat extracted from and rejected to the ground has great imbalance, the ground temperature will deviate from the original temperature with a long term operation. The deviation can reduce GHX performance greatly. As China has vast territory with variety climate, the annual cooling loads and heating loads are different at different places. And the imbalance between the extracted heat and the rejected heat also varies at different places. Therefore, it is necessary to analysis the regional suitability of the ground-coupled heat pump systems. The imbalance between the extracted heat and the rejected heat is analyzed by taking several typical cities in different climates. The new concepts of the Imbalance Ratio and the Extracted Heat to Rejected Heat Ratio are introduced as the weight factors to measure the imbalance in the ground. The values of the Imbalance Ratio and those of the Extracted Heat to the Rejected Heat Ratio are calculated. The optimum range of the Imbalance Ratio is recommended based on the vast investigation of the ground-coupled heat pumps. Some supplemental systems are put forward to supply heat in winter or to reject heat in summer at the places existing serious heat imbalance. The study is very meaningful to the scientific application of the ground-coupled heat pump systems in China.

scholarly journals Finite element modeling of geothermal source of heat pump in long-term operation

2020 ◽  
Vol 154 ◽  
pp. 04003
Author(s):  
Elżbieta Hałaj
Keyword(s):  
Finite Element ◽  
Heat Source ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Transport Model ◽  
Heat Pumps ◽  
Initial Temperature Distribution ◽  
Term Operation ◽  
Borehole Heat Exchangers

Heat pumps become more and more popular heat source. They can be an alternative choice for obsolete coal fired boilers which are emissive and not ecological. During heat pump installation designing process, especially for heat pumps with higher heating capacity (for example those suppling larger buildings), a simulation of heat balance of ground heat source must be provided. A 3D heat transport model and groundwater flow in the geothermal heat source for heat pump (GSHP) installation was developed in FEFLOW according to Finite Element Modelling Method. The model consists of 25 borehole heat exchangers, arranged with spacing recommended by heat pump branch guidelines. The model consists of both a homogeneous, non-layered domain and a layered domain, which reflected differences in thermal properties of the ground and hydrogeological factors. The initial temperature distribution in the ground was simulating according to conditions typical for Europe in steady state heat flow. Optimal mesh refinement for nodes around borehole heat exchangers were calculated according to Nillert method. The aim of this work is to present influence of geological, hydrogeological factors and borehole arrangement in the energy balance and long term sustainability of the ground source. The thermal changes in the subsurface have been determined for a long term operation (30 years of operation period). Some thermal energy storage applications have also been considered.

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.

Peak-Shaving Ratio Analysis of the Natural Gas Combined Heat and Power Plant With Distributed Peak-Shaving Heat Pumps

2017 ◽  
Author(s):  
Xiling Zhao ◽  
Xiaoyin Wang ◽  
Tao Sun
Keyword(s):  
Natural Gas ◽  
Heat Source ◽  
Heat Pump ◽  
Gas Turbines ◽  
Heat Load ◽  
Operating Cost ◽  
Heat Pumps ◽  
Optimized Design ◽  
Peak Shaving ◽  
Gas Price

Distributed peak-shaving heat pump technology is to use a heat pump to adjust the heat on the secondary network in a substation, with features of low initial investment, flexible adjustment, and high operating cost. The paper takes an example for the system that uses two 9F class gas turbines (back pressure steam) as the basic heat source and a distributed heat pump in the substation as the peak-shaving heat source. The peak-shaving ratio is defined as the ratio of the designed peak-shaving heat load and the designed total heat load. The economic annual cost is taken as a goal, and the optimal peak-shaving ratio of the system is investigated. The influence of natural gas price, electricity price, and transportation distance are also analyzed. It can provide the reference for the optimized design and operation of the system.

The Use of Serpentine Earth Coils in Ground Coupled Heat Pump Systems

1984 ◽  
Vol 106 (4) ◽  
pp. 438-446
Author(s):  
P. D. Metz
Keyword(s):  
Thermal Properties ◽  
Heat Pump ◽  
Research Program ◽  
Undisturbed Soil ◽  
Heat Rejection ◽  
Term Operation ◽  
The Earth ◽  
Soil Thermal Properties ◽  
Coil Performance ◽  
Ground Coupled Heat Pump

A research program at Brookhaven National Laboratory (BNL) has studied ground coupling, i.e., the use of the earth as a heat source/sink or storage medium for solar-assisted and stand-alone heat pump systems. As part of this research program, five serpentine earth coil experiments were operated between December 1978 and September 1981. Heat was added to or removed from the earth coils according to weekly schedules based on computer simulations of solar-assisted and stand-alone, ground-coupled heat pump systems operated in the local (New York) climate. Each earth coil was operated according to a different control strategy. This paper presents experimental results from these experiments for the period December 1978 to April 1981, and compares these results to those generated by a comptuer model, GROCS, developed at BNL. The model is found to provide a reasonably good fit to the data, for the most part, using the experimental undisturbed soil thermal properties. In some cases, the use of a lower soil thermal conductivity provides a better fit, particularly during summer months when heat was added to the ground. Thus, given soil properties, GROCS can be used to predict earth coil performance. If given earth coil performance, the model can predict soil thermal properties. Serpentine earth coils are found to be suitable to provide auxiliary heat or heat rejection for solar heat pump systems. In fact, earth coil-based, stand-alone, ground-coupled heat pump systems can provide all heat needed for winter space heating and all heat rejection required for summer space cooling with no need for any auxiliary heating. Subfreezing winter operation is necessary for shallow earth coils in cold climates. No deleterious effects to the ground were observed from the long-term operation of these experiments.

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

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 635 ◽  
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.

scholarly journals The energy source for heat pumps with vertical heat exchangers

2018 ◽  
Vol 44 ◽  
pp. 00157
Author(s):  
Piotr Rynkowski
Keyword(s):  
Heat Pump ◽  
Heat Exchangers ◽  
Electricity Consumption ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Temperature Analysis ◽  
Heat Flows ◽  
Ground Heat Exchangers ◽  
Vertical Heat ◽  
Vertical Ground

The paper presents the ground temperature analysis, heat flows and energy transferred from the soil massif by the vertical ground heat exchangers (VGHE). Three cases – with one, two and three vertical heat exchangers were compared. Their influences on the soil massif temperature in the heat exchangers area were shown. The mass flow and the temperature at the inlet and outlet side of the heat pump were measured in each circuit. Additional, the electricity consumption by the heat pump and energy supply to buffer vessel were measured. Finally, the Coefficient of Performance (COP) as a function of length of VGHE is shown for selected interval time.

scholarly journals Evaluation of long-term operation of combined system for heating the building and preparation of domestic hot water

2018 ◽  
Vol 46 ◽  
pp. 00018
Author(s):  
Dawid Taler ◽  
Rafał Pitry ◽  
Jan Taler
Keyword(s):  
Heat Source ◽  
Heat Pump ◽  
Summer Season ◽  
Hot Water ◽  
Buffer System ◽  
Generation Efficiency ◽  
Combined System ◽  
Term Operation ◽  
Measuring Period

The paper presents, the results of research on the operation and energy efficiency of a 186 kW gas-fired condensing boiler operating in a hybrid heat source system. The boiler co-operates with an 81.1 kW (electric) brine-to-water compressor heat pump, a 27.4 kW air-to-water heat pump and 6 flat solar collectors. A local, built-in, hybrid heat source is located in a public building and is intended to satisfy the building needs. The study was conducted over a period of 1 year - from 1 September 2014 to 31 August 2015. The gas-fired boiler operates in the heating buffer system all year round. The boiler performance is characterized both in the winter and in the summer season, in terms of the amount of heat produced and the heating power. The calculations results of the heat generation efficiency obtained in the measuring period are also presented

Sign in / Sign up

Export Citation Format

Share Document