Analytical Study of Operational Properties of a Plate Shock Absorber of a Sucker-Rod String

Sucker-rod pump plant operation is accompanied by inertial and shock loads, affecting the fatigue strength of sucker rods and causing possible accidents. This work proposes the original design of a shock absorber of a sucker-rod string. The peculiarity of the proposed design is the usage of thin plate packages as a bearing elastic element of the shock absorber. This approach to the elastic element’ design provides the shock absorber to be easy to manufacture and operate. Sucker-rod string protection from extra load will increase the sucker-rod pump plant efficiency in general. This study aims at developing shock absorber’s design and studying its most important performance options—strength and rigidity. A mechanical and mathematical model of a shock absorber’s elastic element was developed in order to specify its deformation. A package of thin plates was modelled as an equivalent solid plate with a cylindrical rigidity providing equal properties of the solid model and the plate package. This model makes possible to describe analytically the stress-strain state of the shock absorber bearing elements. The work presents the final expressions of the shock absorber’s strength and rigidity assessing in a convenient form for engineering practice. The numerical approbation of the obtained analytical results was carried out as the case of a plate elastic element. The authors give recommendation on the bearing unit’s design of the shock absorber.

Application of Hybrid PCM Thermal Energy Storages with and without Al Foams in Solar Heating/Cooling and Ground Source Absorption Heat Pump Plant: An Energy and Economic Analysis

The use of phase change materials (PCM) can be considered an effective way to improve the energy storage capabilities of hybrid water thermal energy storage (TESs) in solar heating and cooling plants. However, due to a few shortcomings, their use is still limited. This paper aims to give a direct estimation of the considerable advantages achievable by means of these hybrid TESs by simulating the annual performance of an existing gymnasium building located in northern Italy. The solar heating/cooling and ground source absorption heat pump plant is simulated using Trnsys. A validated type allows for the simulation of the hybrid water TESs, and also includes the possibility to use aluminum foams to enhance the heat transfer capabilities of the paraffin waxes used as PCM. This paper presents an optimization of the plant design from both energy and economic points of view by considering different cases: all three tanks modeled as sensible (water) storage, or one of the tanks modeled as PCM storage, or as enhanced PCM with metal foam.

Energy Efficiency of the Heat and Power Complex for Highly Efficient Use of the Secondary and Renewable Energy Resources

The article describes a heat and power complex utilizing internal sources of consumer heat, as well as using renewable energy sources. The power complex also includes heat accumulators, cold accumulators and a cascade heat pump plant. This heat pump plant has a high conversion factor of electrical energy due to optimization of heat flows. In this article, a method for determining the energy efficiency of the heat-energy complex under consideration is disclosed.

A Perspective Evaluation Methodology for Economic Feasibility of Low Temperature Sustainable Energy Source in Heating Mode Technology

The economical and clean environment issues for a sustainable energy source at low temperature (LT) were considered and compared to natural gas technology as a fossil fuel source. The friendly environment refrigerants R410A, R407C, R717, R134a, and R600a were analyzed in an approximately 500 kW heating load output cascade heat pump. The heat pump was investigated at an intermediate temperature of 35 °C, high temperature (HT) cycle condenser at 70 °C, and compressors isentropic efficiency of 70%. All analyzed refrigerant pairs exhibited high heating season performance factor (HSPF), and it was ranged between 7 and 8.5. The thermal performance comparison revealed that the HSPF for R717/R600a showed the highest values among other refrigerant pairs. The results showed that at LT cycle evaporator temperature range of −10 to −2 °C, the natural gas technology revealed a higher season heating cost values than that of the heat pump plant by up to 10%. On the contrary at lower LT evaporator temperature, the heat pump plant technology exhibited a higher season heating cost lied in the range of 4–13.6% than that of the natural gas system. At compressors isentropic efficiency of 90%, the seasonal heating cost of the heat pump plant was lower than that of the natural gas technology by the range of 9–25% at test conditions. The mean seasonal CO2 amount released by the natural gas firing technology from all tested refrigerant pairs ranged between 2.1 and 2.5 times that of the heat pump plant technology for the investigated LT evaporator temperature range.